Pliny the Elder [1st century CE] (Natural History, Book 8, 38; 9, 7-8): [Book 8, 38] Accordingly dolphins also, which have on their backs a sharp fin shaped like a knife as if for this purpose, enter the mouth of the Nile, and when the crocodiles drive them away from their prey and lord it in the river as merely their own domain, kill them by craft, as they are otherwise in themselves no match for them in strength. For all animals are skillful in this, and know not only the things advantageous for themselves but also those detrimental for their enemies, and are acquainted with their own weapons and recognize their opportunities and the unwarlike parts of their adversaries. The crocodile's hide is soft and thin over the belly; consequently the dolphins pretending to be frightened dive and going under them rip the belly with the spine described. [Book 9, 7] The swiftest of all animals, not only those of the sea, is the dolphin; it is swifter than a bird and darts faster than a javelin, and were not its mouth much below its snout, almost in the middle of its belly, not a single fish would escape its speed. But nature's foresight contributes delay, because they cannot seize their prey except by turning over on their backs. This fact especially shows their speed; for when spurred by hunger they have chased a fleeing fish into the lowest depths and have held their breath too long, they shoot up like arrows from a bow in order to breathe again, and leap out of the water with such force that they often fly over a ship's sails. They usually roam about in couples, husband and wife; they bear cubs after nine months, in the summer season, occasionally even twins. They suckle their young, as do whales, and even carry them about while weak from infancy; indeed they accompany them for a long time even when grown up, so great is their affection for their offspring. They grow up quickly, and are believed to reach their full size in 10 years. They live as much as 30 years, as has been ascertained by amputating the tail of a specimen for an experiment. They are in retirement for 30 days about the rising of the dog-star and hide themselves in an unknown manner, which is the more surprising in view of the fact that they cannot breathe under water. They have a habit of sallying out on to the land for an unascertained reason, and they do not die at once after touching earth; in fact they die much more quickly if the gullet is closed up. ... For a voice they have a moan like that of a human being; their back is arched, and their snout turned up, owing to which all of them in a surprising manner answer to the name of 'Snubnose' and like it better than any other. [Book 9, 8] The dolphin is an animal that is not only friendly to mankind but is also a lover of music, and it can he charmed by singing in harmony, but particularly by the sound of the water-organ. It is not afraid of a human being as something strange to it, but comes to meet vessels at sea and sports and gambols round them, actually trying to race them and passing them even when under full sail. In the reign of the late lamented Augustus a dolphin that had been brought into the Lucrine Lake fell marvelously in love with a certain boy, a poor man's son, who used to go from the Baiae district to school at Pozzuoli, because fairly often the lad when loitering about the place at noon called him to him by the name of Snub-nose and coaxed him with bits of the bread he had with him for the journey, I should be ashamed to tell the story were it not that it has been written about by Maecenas and Fabianus and Flavius Alfius and many others, and when the boy called to it at whatever time of day, although it was concealed in hiding used to fly to him out of the depth, eat out of his band, and let him mount on its back, sheathing as it were the prickles of its fin, and used to carry him when mounted right across the bay to Pozzuoli to school, bringing him back in similar manner, for several years, until the boy died of disease, and then it used to keep coming sorrowfully and like a mourner to the customary place, and itself also expired, quite undoubtedly from longing. - [Rackham translation]

Aelianus [170-230 CE] (On the Characteristics of Animals, Book 1, 18): ...though one confront [the mother dolphin] with terrors never so great, she is still undismayed, and will not endure to desert her young one which has come to a bloody end; indeed, it is even possible to strike her with the hand, so close does she come to the hunters, as though she would beat them off. And so it comes about that she is caught along with her offspring, though she could save herself and escape. But if both her offspring are by her, and if she realizes that one has been wounded and is being hauled in, as I said above, she pursues the one that is unscathed and drives it away, lashing her tail and biting her little one with her mouth; and she makes a blowing sound as best she can, indistinct, but giving the signal to flee, which saves it. So the young dolphin escapes, while the mother remains until she is caught and dies along with the captive. - [Scholfield translation]

Gaius Julius Solinus [3rd century CE] (De mirabilibus mundi / Polyhistor, Chapter 12.3-6): [Chapter 12.3] This area harbors very many dolphins. These creatures provide multifarious causes for wonderment. First of all, the seas have nothing more speedy; many of them leap up and fly over the sails of ships. Wherever they go, they go in couples. [Chapter 12.4] They beget young; the unborn offspring mature in nine months. The babies are born in summertime, and the mothers nourish them with their teats. When the babies are very young, the mothers take them into their mouths. The mothers follow their babies for some time while they are still weak. Dolphins live for thirty years, as has been investigated in an experiment, wherein some specimens’ tails were chopped off. Dolphins do not have their faces in the same place as other marine creatures do -- they are almost in their stomachs. Unlike other aquatic animals, they can move their tongues. [Chapter 12.5] They have sharp dorsal fins, which bristle up when they become angry, and are concealed, as in a sheath, when their minds are in repose. They say that dolphins do not breathe underwater, and they do not take in the breath of life except in the air above. For a voice, they have a moan similar to that of a human being. They are appropriately named “Snubnose”. This name pleases them, and they follow those who call them by it. [Chapter 12.6] Dolphins hear men’s voices more easily when in the breezes of the north wind; contrariwise, their hearing becomes blocked up when the wind is blowing from the south. They are delighted by music: they rejoice in the songs of the tibia. Wherever there is harmony, they arrive in throngs. - [Arwen Apps translation, 2011]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 6:11): Dolphins [delphin] have their appointed name because they follow the voices of humans, or because they gather in a group at the sound of music [symphonia]. Nothing in the sea is faster than they are, for they often jump over ships as they leap. When they play in the billows and dash themselves headlong against the mass of the waves in their leaping, they seem to portend storms. Properly, they are called simones. There is a kind of dolphin in the Nile with a saw-tooth back; it kills crocodiles by cutting the soft parts of their bellies. - [Barney, Lewis, et. al. translation]

Alexander Neckam [1147-1217 CE] (De naturis rerum, Book 2.27-29.): [Book 2.27] Dolphins are very swift, and therefore they are said to draw the chariot of Thetis. They are said to offer assistance to the shipwrecked, and are said to be caught and delighted by the sweetness of musical instruments. They are also prone to cry when they are caught. [Book 2.28] There is nothing faster in the sea than dolphins, so that they often leap and fly over the sails of ships. Mated couples wander together and suckle their young. They give birth after ten months. Lucan says this happens in the summer. They nourish their young with their breasts, and when the babies are young they them into their mouths. They live to their thirtieth year. Their mouths are not in the same place as in other beasts, but in their bellies. Its voice is a groan, like a human. When they hear a certain name, they follow the callers, for properly they are called sinomones [simones: flat nose, snubnose]. They hear the voices of people more easily when a north wind is blowing, but with a south wind their hearing is obstructed. They rejoice in music, especially the music of the pipes, and wherever there is harmony they come in flocks. [Book 2.29] There is also a race of dolphins in the Nile, whose backs have serrated crests. These dolphins lure crocodiles to swim, then by cunning dive below them and cut their tender underbelly and kill them. - [Wright/Badke]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Marine monsters 6.15, 6.16, 6.41, 7.31): [Thomas describes the dolphin under the names delphinis, plataniste and delphinorum.] [Marine monsters 6.15] There are dolphins in the sea, as James and Solinus say, of a multitude of species. The sea has nothing faster than these beasts. And except that its mouth is below its beak, almost in the middle of his belly, no fish could escape his speed. But providential nature causes a delay, because unless they are on their back and turned over they are not able to catch or hold anything. After their tenth month they give birth. But the males devour the young to which the females give birth, so the mothers hide themselves with their children. For they love them very tenderly, and lead them for a long time behind them, and follow their young under the water. But when the children have reached the age of strength, unless they are strong, even their mothers also persecute them. The children of dolphins, as Aristotle says, grow quickly and always grow up in ten years. The young themselves enter into intercourse at the end of ten months and are impregnated. Dolphins give birth only in summer, never in winter. They feed the children with their breasts. In the meantime, they receive tender young in their mouths. But they do not have their mouths in the same place as other beasts, but they have them in their bellies, and contrary to the nature of aquatic animals they only move their tongues. They have spines on their dorsal fins, and they make them shake when they are angry; but when they are at peace, they are covered with certain receptacles. They cannot breathe in the waters, and recover the vital breath only in the air above. Instead of a voice it moans like a man; and this because they have lungs and rough veins; and their tongue is not complete, nor do their lips come forth to distinguish a voice. They have no ears, but a hole instead of ears. Dolphins do not have the sense of smell, nor do they have traces, although they smell very keenly [?]. They sleep on the water, and they can be heard snoring. They live to the greatest number of years, namely up to a hundred and forty years, and this the Experimentator says, after their tails are cut off. They are made to hear more sharply the wind of the North; the sound of wind blowing in the south is blocked. They are filled with music, they rejoice with the music of the flutes, and wherever they hear this, they come in flocks. As sailors were preparing to kill Arrion, a man of the lyre, he begged them that he should first play the lyre. To that song a flock of dolphins assembled, when he had thrown himself into the sea, was taken up by one of them and carried to the shore. Only the dolphin, as Aristotle says, lacks gall. The small dolphins are always together in herds and have two large dolphins as guardians. But if one of them dies, the others carry it on their shoulders and guard it, until it is driven ashore by a storm of the sea. But they guard their dead, lest it be eaten by other fishes. For they love each other in a marvelous way. Whence Pliny testifies, it is told that, after a dolphin had been captured by King Charles, a great multitude of the rest assembled at the port, where the dolphin was kept tied. When they were lamenting and as if begging for mercy, the king ordered it to be released. If any one eats the flesh of a dolphin, as the Experimentator says, and if he has fallen into the sea, if he is found by the dolphins, they immediately devour him. But if he does not eat dolphins, they lift him up on their beaks and drag him to land and defend him from other fish. But how this happens, so that the dolphins know the eating of flesh in man, I cannot see, unless this also is a secret of nature, in which, as in many other things, the wonders of God are foretold. The dolphins are followed by multitudes of other fish, and the fishermen know that and hunt the fish where they have passed. Under the prince Augustus, a boy in Campania first enticed a dolphin with pieces of bread, and it finally trusted itself to be fed by hand; afterwards, when the boy had gained boldness, he jumped on the dolphin's back and was carried off by him. At first this was a wonder to the beholders, but at last it was so long continued by the constant spectacle that it ceased to be a miracle. But many years after the boy died, when the dolphin did not see him returning in his usual way, and waited for him to come to a certain place, the dolphin perished under the eyes of the common public. This Macenatus, Fabianus (and Solinus) include in their texts. At the city of Hippo, in Africa, by the sea, a dolphin was fed by the Hipponians, and he offered himself to be treated, and made frequent gestures. Flavianus, the proconsul of Affrice, having anointed it with perfumes, it was tossed about by the waves as if dead, drowsy with the novelty of the scent. Historia Persarum: In the city of Jasus in Babylonia, a boy fell in love with a certain dolphin, whom, while it was following him impatiently as he retreated after his usual quarrels, was stuck in a sandbar. Likewise, near the same city, there was another boy named Herianus, who was in the same way in the sea, and when a raging wave killed the boy, the dolphin brought him back to the land and, as if confessing its guilt, punished itself with death. [Marine monsters 6.16] There is another kind of dolphins in the river Nile, whose backs have serrated crests. These dolphins entice the crocodiles by their eagerness to swim, and while they are swimming under the waves they deceive and kill them by their fraudulent cunning. For they cut the tender bellies of the crocodiles with their serrated crests and kill them. Crocodiles see poorly in water, but on land they see more acutely. [Marine monsters 6.41] Plataniste are the marine animals, according to Pliny, that live in the river Ganges of India. Dolphins have a beak and a tail. They are sixteen cubits in length. [At this point Thomas mistakenly continues with Pliny's account of the ceruleum which he already covered in Marine monsters 6.13] [Marine monsters 7.31] There is another race of dolphins [delphinorum] in a smaller form, as Isidore says, from the wild dolphins, which appear to play on the surface of the water when a storm is imminent. By this information the sailors foretell that storms are coming. They flourish so much on the agility of their bodies that they even fly over ships. - [Badke translation/paraphrase]

Bartholomaeus Anglicus [13th century CE] (Liber de proprietatibus rerum, Book13.26): ...that hath milke, and giveth her children sucke while they are little, as Aristotle sayth, lib. 6. And Isidore. libro. 12. cap. 6. sayth, that the Dolphins bée called Symphones also, & they have that name, for they followe mans voice and come together in flocks to the voice of the simphonie, and having liking in harmonie: and in the sea is nothing more swifte then Dolphins bee. For oft they startle and overleape ships, whose leaping and plaieng in the wuce of the sea betokeneth tempest. And in the river of Nilus is a kinde of Dolphins with ridges, thoothed as a Sawe, that cutteth the tender wombes of Crocodiles, and slayeth them, as Isidore sayth. ... Also hee saith, that Dolphins know by the smel, if a dead man yt is in the Sea eate ever of Dolphins kinde: & if the dead man hath eaten therof, he eateth him anone: & if hee did not, he kéepeth and defendeth him fro eating & biting of other fish. And shoveth him & bringeth him to the cliffe with his owne wroting. - [Batman]