THE MAMMALIA. 49 



Viverrine Dog (Cynodictis) 



, I 



Viverrae 



1 . 



Plesictis 

 Stenoplesictis 



Prgelurus Palseoprionodon 



I I 



Pseud^lurus Weasels 



I 



Cats 



I 



Sabre-toothed tiger 



It will be sean that two ancient forms, with the dentition of 

 dogs, were the ancestors of the dogs, bears, cats, and weasels ; 

 Cynodictis of the more highly specialised Carnivores, and Amphi- 

 cyoii of the wolves and bears. 



The Cetacea (whales and dolphins, etc.) are, as Nicholson"says, 

 " not particularly interesting from a palaeontological point of 

 view," insomuch that the remains of comparatively few extinct 

 species are to be found. Their fullest development occurred in 

 the Miocene period, when there were both large and small whale- 

 bone whales (the small from two to ten feet long), dolphins, and 

 the two entirely extinct genera, Zeuglodofi and Squalodo7i. They 

 have rather increased than diminished in size in modern times ; 

 the modern whale sometimes reaching a length of from 90 to 100 

 feet. But from the point of view of evolutionists, the Cetacea 

 present some extraordinary and (so far) insoluble problems. 

 Certain points in the Cetacea bring them close to the primitive 

 hoofed animals — for instance, the " complex stomach, the simple 

 liver, the respiratory organs, but mainly the reproductive organs." 

 That the whale is in every respect, but in that of outward adapta- 

 tion to an aquatic life, a true Mammal, everyone knows. That it 

 once possessed four legs is also evident from the rudimentary 

 pelvic bones, and last remnant of a thigh bone in the modern 



Journal OF Microscopy and Natural Science. 



New Series. Vol. II. i88q. » 



