86 MAMMALIAN DESCENT. [Lect. III. 



the Siluras kind (Ari//,'<, &c.) lay a few large eggs — as large as a 

 small cherry — and as these fishes have in them tlie beginnings 

 of family affection, and yet are nomads, travelling about a good deal, 

 np and do^vn mountain streams, the male pockets those precious 

 globes in his mouth, ^\'hilst he and his mate wander about, laying them 

 down whilst they rest. 



The Amphibia (Xewts and Frogs and their kindred) lay small eggs, 

 as in the Lamprey, Avith but little food-yolk, but a number of 

 curious family arrangements arc to be seen in these groups. 



The Common Frog lays multitudes of eggs, and each of these at 

 first is covered with a tenacious jelly, which, swelling with the water, 

 expands to the size, and has the appearance, of a white currant ; thus 

 an egg-cup-full of eggs soon grows into a mass that Avould fill a 

 quart measiire, each Avhite globe having a blackish egg inside, the 

 size of a mustard-seed. The father and his wife hang about these, their 

 future progeny, until they are hatched, but do not seem to under- 

 stand the meaning of them, or that they are being eaten, by 

 hundreds, by the Duck, whose voice might seem to indicate a Eanine 

 descent. As for the Obstetric Frog, the male coils the slimy eggs 

 round the thighs of the female, and she swims about with them 

 attached to her, a family arrangement not unlike what we see in the 

 Shrimp and her kindred. 



But these tail-less metamorphosing Amphibians, that in their 

 transformation give us the promise, or anticipation, of much iui 

 finds its culmination in our own body, have also some very remark- 

 able ways of showing their social and parental affe<;tion and care. 



This extremely ancient family holds its o-vn\, and kee})s its place, 

 in the presence of all the newer and nobler types of Yertebrata. 

 Their fecundity enables them to lose a large proportion oi their 

 progeny without diminution of their actual numbers, year by year, 

 a considerable percentage slipping through the fingers, and out 

 of the very mouth oi fate. Moreover, we yearly see our common 

 kinds takiiig hold of the forelock of time, and getting their wiiter- 

 bred brood out of the way before the drought can kill them. 



Some of the foreign races have very curious habits. 



" In Notodel^Ms ovipara the eggs are transported (by the male ?) 

 into a peculiar dorsal pouch of the skin of the female, which has an 

 anterior opening, but is continued backwards into a pair of diverticula. 



