48 A SYNOPSIS OF ANIMAL CLASSIFICATION. 



Sub-class II. EUTHERIA Cloaca divided transversely into 



intestinal and genito-urinaiy tracts ; 

 mammae furnished with nipples; 

 viviparous, early development takes 

 place in uterus; no episternum; 

 coracoid reduced and fused \?ith 

 scapula in adult. 



Group A. Marsupialia (Didelphia) . . Division of cloaca seldom 



complete. Young are born in an 

 immature condition and sheltered 

 in an external integ^mental pouch 

 (jnarsupium) on the ventral surface 

 of the abdomen; two lateral uteri 

 and vaginae, sometimes incom- 

 pletely united. 



Order i. Polyprotodontia More than three incisors on each 



half of upper jaw. 



X Didelphys, Perameles. 



Order 2. Diprotodontia Three incisors, or less, on each 



half of upper jaw. 



X Macropus, Phascolomys. 



Group B. Placentalia (Monodelphia) . . Young nourished in uterus 



of mother by a capillary mass, the 

 placenta, which adheres to the 

 uterine wall and is connected with 

 the embryo by the umbilical cord. 

 Anus separated from the uro-genital 

 sinus by a perinceum. 



Order 3. Edentata Teeth either wanting or in con- 

 dition of retrogressive metamor- 

 phosis. Incisors and canines gen- 

 erally fail . Large number of sacral 

 vertebras. Placenta indeciduate, 

 diffuse, or occasionally discoidal. 

 X Dasypus. 



Order 4. Sirenia Aquatic forms with only the ante- 

 rior limbs developed. Teeth often 



