30 COMPARATIVE ANATOMY 



Sub-order Anthropoidea. Anthropoids include the remainder of the 

 primates. Hands and feet are differentiated, and either the thumb or the 

 great toe is opposable. Finger and toe-nails are flat, except in the marmo- 

 sets which have claws. 



Three chief sections of anthropoids are recognized: 



Platyrrhina. The South American monkeys, with broad nasal septum, 

 three premolar teeth in each half-jaw (except the marmosets which, like 

 the Old World monkeys, have two), and a climbing foot. 



Catarrhina. The Old World monkeys and the great apes, with a 

 narrow nasal septum, two premolar teeth, and a climbing foot. 



Bimana. Also with narrow nasal septum and two premolars, but 

 with the great toe non-opposable and a walking foot. 



CLASSIFICATION OF ANIMALS— SUMMARY 

 Animal Phyla 



1. Protozoa. Unicellular. Reproduce by fission. 



METAZOA, multicellular. 



2. PoRiFERA. Multicellular. Acoelomate. Pores in body-wall. 



3. CoELENTERATA. Multicellular. Acoelomate. Radial symmetry 

 may possibly disguise primitive bilateral symmetry. Two-layered body- 

 wall. Nettling-cells. Enteron with single opening. 



4. Platyhelminths. Bilateral. Flat-bodied. Without coelom. 

 Anus in a few genera. 



5. Nemathelminths. Pseudocoelomate. Cylindrical. Anus. 



6. MoLLUSCOiDA. Usually coelomate. U-shaped alimentary canal. 

 Lophophore. 



7. Rotifera. Pseudocoelomate. Trochophore-like worms. CiHa 

 around mouth. 



8. Echinodermata. Coelomate. Spiny-skinned. Water-vascular 

 system. Bilateral symmetry disguised. 



9. Annelida. Coelomate. Metameric. Appendages when present 

 without joints. 



ID. MoLLUSCA. Coelomate. Non-metameric. Mantle, mantle-cav- 

 ity, foot. 



11. Arthropoda. Pseudocoelomate. Metameric. Jointed append- 

 ages. 



Classes; Crustacea, Arachnida, Onychophora, Myriapoda, Insecta. 



12. Chordata. Notochord. Dorsal tubular nervous system. 



Sub-Phyla of Chordates 



Hemichorda. Notochord limited to oral and pre-oral region. Worm- 

 Hke. Body in three primary divisions. Balanoglossus. 



