Plutarch, De sollertia animalium
Goodwin, Ed.

Then again, the care of their young is common to both sexes. For the males never devour their offspring, but remain and abide constantly by the spawn, protecting it with a diligent watchfulness, as Aristotle relates; and those that accompany the females moisten the spawn with a small quantity of milky seed; for that otherwise the spawn will not grow, but remains imperfect and never arrives at the due proportion. Particularly the fish called phycides make themselves nests in the seaweed to preserve their spawn from the waves.

But the love of the galeus toward her young ones is beyond the affection and clemency of any the tamest of creatures; for they lay an egg, which being hatched, they nourish and carry the young about not outwardly, but within their own bowels, as if they could not breed their young without a second birth.

When the young ones are somewhat grown, they put them forth again, and teach them to swim close by themselves, then resume them again through their mouths into their bellies, and afford them nourishment and safe retirement in their bodies, till they are able to shift for themselves.

No less admirable is the care of the tortoise, as to the bringing forth and preserving her young. For she retires out of the sea to lay; but not being able to stay long upon the land, she hides her eggs in the sand, covering them over gently with the lightest of the gravel; and when she has thus sufficiently and assuredly concealed them, some report that she marks and streaks the place with her feet, that she may be able to know it again; others affirm that the female, being turned upon her back upon the sand by the male, leaves her particular marks and signatures behind her. However it be, this is most wonderful, that after waiting forty days (for in so many the eggs come to break) she returns, and knowing where the treasure lies, as well [p. 210] as any man understands where he hides his gold, she opens them with great joy and alacrity.