DEFINITIONS OF SYSTEMATIC NAMES. 



383 



Marsupialia, subclass of mammals with 

 pouch for young, opossums, kangaroos, 

 etc. 



Megalops, genus of fishes including the tar 

 pon. 



Melanerpeton, genus of extinct stegocephal 

 amphibians. 



Monodelphia, subclass of mammals, in- 

 cluding all except monotremes and 

 marsupials. 



Monotremata, subclass of mammals with 

 cloaca; includes duckbill and Echidna 

 of Australia. 



Morones, genus of catfishes. 



Mugil, genus of fishes, mullets. 



Mustelus, genus of small sharks; dogfish. 



Myrmecobius, genus of Australian mar- 

 supials. 



Myxine, genus of cyclostomes; hag fishes. 



Myxinoids, group of Cylostomes; hag 

 fishes. 



Necturus, genus of aquatic amphibians 

 with tail and external gills, central U. S. 



Xotidanids, sub-order of sharks with more 

 than five gill clefts. 



Xototrema, genus of South American toads 

 with dorsal brood sac. 



Ophidia, sub-order of reptiles; snakes. 



Opisthocomus, South American bird, type 

 of a separate sub-order. 



Opisthodelphys, genus of tropical American 

 tree-toads. 



Ornithorhynchus, genus of monotremes; 

 duckbill of Australia. 



Ostariophysi, bony fishes with Weberian 

 apparatus. 



Ostracoderms, a group of extinct verte- 

 brates of very uncertain position. 



Palaeohatteria, a fossil reptile allied to 

 Sphenodon. 



Palaeospondylus, a problematical fossil 

 vertebrate from Scotland. 



Perennibranchs, tailed amphibia which 

 retain the gills through life. 



Perissodactyls, sub order of mammals with 

 odd number of toes; horses, rhinoceros, 

 tapirs. 



Petrobates, genus of extinct theromorph 

 reptiles. 



Petromyzonts, subclass of cyclostomes, 

 lampreys. 



Phoca, genus of carnivores including com- 

 mon seals. 



Physoclisti, fishes in which the air-bladder 

 is closed. 



Physostomi, group of fishes in which the air- 

 bladder has a duct; mostly fresh water. 



Pipa, tongueless toad from South America. 



Pisces, the class of fishes. 



Placentalia, all mammals (except marsupials 

 and monotremes) in which a placenta 

 occurs. 



Placodus, genus of extinct theriomorph 

 reptiles 



Plesiosaurs, order of extinct, long-necked 

 swimming reptiles 



Polyodon, genus of ganoid fishes, paddle 

 fish. 



Polypterus, genus of ganoids from Africa. 



Porichthys, genus of fishes from Pacific; 

 midshipman. 



Primates, highest order of mammals, 

 including monkeys, apes and man. 



Pristiurus, genus of European dogfish. 



Proboscidea. order of mammals, including 

 elephants. 



Procolophon, genus of extinct theromorph 

 reptiles. 



Proteus, genus of tailed amphibians from 

 caves of Austria, allied to Necturus. 



Protopterus, genus of dipnoi from Africa. 



Psittacus, genus of parrots. 



Pterodactyls, extinct flying reptiles. ' 



Pterosaurs, extinct flying reptiles, ptero- 

 dactyls. 



Pythonomorphs, a group of extinct swim- 

 ming reptiles. 



Raia, genus of elasmobranchs, including 

 the skates. 



Rana, genus of amphibia, frogs. 



Ratitae, birds without keel to sternum, 

 ostriches. 



Rhea, three- toed South American ostrich. 



Rhynchobatus, genus of tropical skates. 



Rhynchocephalia, order of lizard-like rep- 

 tiles; Sphenodon of New Zealand only 

 living species. 



Rodentia, order of mammals with gnawing 

 teeth, rats, rabbits, beaver. 



Ruminants, group of ungulate mammals 

 which chew the cud. 



Salamandra, genus of tailed amphibia from 



Europe. 

 Salamandrina, order of tailed amphibians 



without gills. 

 Salmonids, family of fishes including trout 



and salmon. 

 Sauropsida, class of vertebrates including 



reptiles and birds. 

 Sceleporus, genus of lizards of eastern 



United States. 



Scomber, genus of fishes; mackerel. 

 Scorpaenichthys, genus of sculpins. 

 Selachii, order of elasmobranchs; sharks. 

 Serranidae, family of marine, perch-like 



fishes. 

 Siluroids, order of fishes containing the 



cat-fishes. 

 Siren, genus of tailed amphibian from U.S. 



with external gills. 



