Lect. IV.] GIGANTIC SLOTHS. 115 



fruitful harvest of these types, only partially hid some of the most 

 precious of his spoils. 



Things at their height are ready to decline. The Edentata 

 itndoubtedly arose to their height or culmination, as a group, at the 

 end of the ages just before our own time ; hut their decline has 

 been fearfully rapid. Judging from the size of the pelvis of the 

 Megatherium, and, remembering what has just been said about 

 the large size of the new-born Aard-vark and Pangolin, we may 

 suppose that the young of that giant, at birth, must have been very 

 large indeed. So large, I suppose, that if, indeed, the old and the 

 new Sloths co-existed, the young of the former would seem fit to' be 

 the parents of the latter ; they — the Ai and the Unau — although 

 adult, would have looked mere kittens beside the huge suckling of 

 the Megatherium. 



There is, however, much more to be spoken of in this matter than 

 the mere size of these extinct types as compared with their dwarfed 

 modern representatives. 



The Megatherium and the Mylodon were not pure Sloths ; 

 the Glyptodon was not a pure ArmadUlo ; they were more generalised 

 than the lower forms, and to understand them, we must compare 

 them, not with the living kinds in their adult state, biit in their 

 embryonic stages. This is the special, and not easy, work of the 

 morphologist; a piece of work, on these very forms, is likely to see 

 the light in the coming winter, and the reader may then take 

 up the details which wiU be laid before him. The features of the 

 ^Mjfgatherium may be seen in miniature in the face of an embryo 

 Unau; but, more than this, that embryo shows, most unmistakably, a 

 likeness to the family of the Ant-bear. The latter, the longest- 

 faced creature living, — that gigantic mammalian Weevil, with his 

 hairy body, and curiously out-drawn long slender face, — has a shorter- 

 faced relation not larger than a Squirrel : this is the climbing Little 

 Ant-eater, with a prehensile tail like that of a Spider Monkey. That 

 kind, whilst still young, has a skull which has most remarkable points 

 of resemblance and affinity with that of the early embryo of the Two- 

 toed Sloth (Unau, Choloepus), which, then, has a longish face, whereas 

 when adult, it is curiously and almost absurdly short. So that I can 

 read some tokens of the Ant-eater, as well as of the Megatherium, in 

 the nascent face of the existing Sloth. Mark another point well 



