COMPARATIVE AXATOMY. 86 



false molars, or pn-molars, corresponding in position with the 

 molars of the first set of teeth, the deciduous, or milk teeth ; 

 three Irue molars or grinders. 



The whale however has no teeth, but instead, that curious 

 horny elastic substance that we incorrectly call whalebone. 



In the ant-eaters, there are no teeth at all, while the arma- 

 dillo has ninety-six, and some of the dolphins have a hundred 

 and fifty. 



I will now call your attention to this diagram, showing 

 Owen's classification of the mammalia ; and will, as far as my 

 specimens allow me, go through them class by class. 



Subclasses. Orders, 



Archencephala Bimana. 



'tt • 1 * ( Quadrumana. 

 Unguiculata \ ^ 



° \ Carnivora. 



C Artiodactyla. 



Gyrcncephala ^ Ungulata ) Probosddfa^'^" 



(^ Toxodontia. (fossil.) 

 TIT i-i * ( Sirenia. 



L^'^t^l^^^ i Cetacea. 



Lissencephala \ Cheiroptera. 



^ ) Insectivora. 



Bruta. 

 Cheirc 

 Insect 

 Rodentia. 



^ ^ ( Monotremata. 



First. The Bimana of which man is the only representative. 

 The dental formula in man is written thus : — * 



2 — 2 I 1 2 — 2 3 — 3 



I C PM M 32 



2 — 2 I — I 2 — 2 3 — 3 



Second. The Quadrumana which include the cattarhine or 

 old world monkeys, which are found in Africa, Asia, and the 

 rock of Gibraltar, have the same number of teeth as man ; the 

 number of molars and premolars respectively being reversed. 

 The platyrrhine or new world monkeys, which have four more 

 teeth than those of the old world ; they have also prehensile 



* I. Stands for Incisors. C. Canines. P.M. Premolars. 

 M. Molars 



