Lect. VIII.] AQUATIC MAMMALS. 190 



Tlijracoids and Frohoscidea. 



An embryo of the Elephant is still a desideratum to 

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

 little Syro-African Coney, not Cuniculus or Rabbit. 

 My esteemed friend, the late Professor Rolleston, sent 

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

 I learn that no larsfe amount of cuttino- and contrivino; 

 will lie necessary to make this type of skull fit in with 

 that of other low and generalised forms. With this 

 skull I shall in due time compare that of the 

 Chevrotains or Tragulidte, 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. 



Palseontology 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 Ijecome simply monstrous. The Sirenia 

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

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

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

 fallen from the ranks of life. 



