Lect. VIII.] AQUATIC MAMMALS. 199 



Hyracoids and Proboscidea. 



An embryo of the Elephant is still a desideratum to 

 me, in my special work, and so is that of the Hyrax — the 

 little S3n-o-African Coney, not Cunictdus or Eabbit. 

 My esteemed friend, the late Professor EoUeston, sent 

 me the skull of a new-born Hyrax, and from that 

 I learn that no large amount of cutting and contriving 

 will be necessary to make this type of skuU fit in with 

 that of other low and generalised forms. With this 

 skull I shall in due time compare that of the 

 Chevrotains or Tragulidse, the older types of Ruminants. 



Cetacea and Sirenia. 



As to the Cetacea and Sirenia, there must be much 

 slow and cautious work and thinking before we shall 

 be able to relegate them to their proper place in the 

 class. 



Palaeontology is as unready here as embryology. That 

 these forms have undergone great changes during long 

 periods of time, there can be no doubt ; they have 

 many of them lost their teeth ; all have lost their hind 

 limbs ; their fore-face has grown into a huge beak, and 

 their bulk has become simply monstrous. The Sirenia 

 — Manatee and Dugong — are as great a mystery as the 

 Cetacea. They are almost extinct ; the largest of them, 

 the Rhytina, of the seas north of Asia, has only lately 

 fallen from the ranks of life. 



