IGO MAMMALIAN DESCENT. [Lect. VI. 



small ; they are quite normal, and the stapes (stirrup) is 

 well shaped, with a large foot-hole ; the rest of the hyoid 

 arch is complete. The tympanic annulus, or ring-bone 

 of the ear-drum, is rather slender, hut has a Lroad flange 

 on its hinder cms or limlj ; there is only a low ridge on 

 the l)asi-s2:)lienoid (skull-halk), helping to wall in the 

 f-avum tympani, or drum cavity ; the concha or free 

 }>art of the ear is well developed. Thus we miss in this 

 diminutive type the cheek-hones (malars or jugals), and 

 the tym^^anic wings of the hasi-sphenoid ; these parts 

 have gone in the general reduction of the type ; they 

 have become small by degrees, and beautifully less, 

 through the secular periods during which the Eutheria 

 have been struggling upwards. 



The ripe embryo, and the embryo when five-sixths 

 ripe, are like little generalised. Pigs, but their snout is 

 oljtuse, not discoidal, as in those rooting beasts. In their 

 general appearance both the emljryos and the nestlings 

 mioht be taken as models for the restoration of the 

 forms whose skeletons are found in the Upper Eocene 

 deposits ; only in size do they come short ; some of those 

 lost types {Palceotherium, Anoplotheriiim) were cattle 

 of considerable dimensions. The probability is that the 

 Shrews have, on the whole, kept most of their original 

 characters as early Eutheria ; but that they have under- 

 gone, besides gradual lessening of bulk, gentle changes 

 of structure, in conformity with their habits. Their 

 safety during all this time has been due to the fact that 



