CLASS MAMMALIA. MAMMALS 



495 



Figure 368. Timber wolf [Canis). A cousin to 

 the dog, and of high intelhgence. It is now becom- 

 ing scarce in some places where it was once abun- 

 dant. (Courtesy of N.Y. Zoological Society.) 



A BRIEF CLASSIFICATION 

 OF LIVING MAMMALIA 



{For reference purposes only) 



Class Mammalia. Mammals or "animals" 

 are warm-blooded; possess hair at some stage of 

 existence; and have mammary glands in the 

 female, which secrete milk to nourish the 

 young. Approximately 5000 species. 



Subclass 1. Prototheria. Egg-laying mam- 

 mals. They are confined to Aus- 

 tralia, Tasmania, and New 

 Guinea. The two oviducts open 

 directly into a cloaca along with 

 the intestine and urethra, as in 

 birds and reptiles; in certain re- 

 spects the skeleton agrees with 

 that of the reptiles. 

 Order 1. Monotremata. Monotremes. 

 Exs. Ornithorhynchus ana- 

 tinus, duck-billed platypus 

 (Fig. 352A); Tachyglossus, 

 spiny anteater (Figs. 337 and 

 353). 

 Subclass 2. Theria. Mammals bearing the 

 young alive. 



Infraclass 1. Metatheria. The young are 

 born in a very immature 

 condition and are carried in 

 a marsupium or pouch; usu- 

 ally no placenta. 

 Order 1. Marsupialia. Marsupials. They 

 possess abdominal pouches or 

 marsupia in which they carry 

 their immature young. Exs. 

 Didelphis marsupialis, Ameri- 

 can opossum; Phascolarctus, 

 koala (Fig. 355). 

 Infraclass 2. Eutheria. Mammals with an 

 efficient placenta attached to 

 wall of uterus. The young 

 are born in an advanced 

 stage. 

 Order 1. Insectivora. Insectivores. 

 Moles, shrews (Fig. 337) 

 etc. 

 Order 2. Dermoptera. "Flying le- 

 murs." Ex. Galeopithecus 

 volans, flying lemurs (Fig. 

 337). 

 Order 3. Chiroptera. Bats (Fig. 337). 

 Ex. Myotis lucifugus, little 

 brown bat, flying mam- 

 mals. 

 Order 4. Primates.* An arboreal off- 

 shoot of the primitive pla- 

 cental stock. Ex. Baboon 

 (Fig. 337). 

 Suborder 1. Lemuroidea. Lemurs. 



Ex. Lemur varius. 

 Suborder 2. Tarsioidea. Tarsiers. 

 Transitional between le- 

 murs and monkeys. Ex. 

 Tarsius spectrum. 

 Suborder 3. Anthropoidea. Monkeys, 

 apes, and man. Ex. 

 Homo sapiens. Mam- 



* The position of the primates in the midst of 

 the mammalian series instead of at the end, where 

 they are sometimes placed, may seem strange to 

 students, but man, the apes, and other mammals 

 belonging to this group retain a larger number of 

 primitive characters tlian do the orders that are 

 placed below them in this classification. The pri- 

 mates excel principally in the development of the 

 nervous system, but are comparatively primitive 

 when the bones, muscles, teeth, and other organs 

 are taken into account. 



