COMPENDIUM OF GENERIC DISTINCTIONS. 



049 



Genus. — Trichecns. 



Teeth. — Upper canines enormously developed, and without 

 roots. 



Head. — Muzzle tumid and protuberant, covered with thick 

 bristles — External ears wanting. 



Genus. — Morunga. 



Teeth as in Stemmatopus. 



Head. — Proboscis-like expansion of nose. 



Genus. — Arctocephalus. 



Teeth.- 1. ?=?, C. — , P. — , M. — (or rarely — ) 

 2—2 1—1 3—3 2—2 V 2—2 / 



= 34. Four upper and middle incisors broad crowned, with 



groove, two others conical. 



Limbs. — First toe of fore-feet longest, the middle hinder toes 



nearly equal ; membrane of hinder feet projecting like leathern 



straps beyond the toes. 



Order. — CETE. 



Teeth. — When present, conical and similar, the palate frequently 

 furnished with baleen. 



Body shaped like a fish. 



Limbs. — Short and fin-shaped, the hinder pair forming a hori- 

 zontal tail. 



Skin. — Smooth and hairless, nostrils developed into blowing- 

 tubes. 



Family.— BALjkmnM. 



Nostrils two, palate with baleen, jaws without teeth. 

 Head. — Very large, equal to one-third the size of the body. 



Genus. — Balsena. 



No dorsal fin, abdomen smooth, baleen very long. 

 Teeth. — None in adult, only rudimentary in young. 



Genus. — Megiiptera. 



Dorsal fin, abdomen furnished with longitudinal folds, pectoral 

 fins long, equalling the head in length, baleen short, broad, and 

 triangular. 



Genus. — Balsenoptera. 



Dorsal fin sharp and falcate, abdomen and throat furnished 

 with longitudinal folds, pectoral fins moderate, baleen short. 



Genus. — Physalus. 



Dorsal fins falcate, pectorals moderate, abdomen and throat 

 with longitudinal folds. Blow-holes semi-lunar, divided from 

 each other by a groove, and covered with a valve or flap. Baleen 

 6hort. 



Family. — Catodontid^;. 



Head very large, upper jaw apparently toothless, the lower jaw 

 furnished with many conical teeth, which are received into cav- 

 ities in the upper jaw. Blow-holes united, with a semi-lunar 

 opening. 



Genus. — Catodon. 



Dorsal hump rounded, blow-holes in front of the head. 

 Head.— Blunt at muzzle, skull much elongated. 



Genus. — Physeter. 



Upper jaw longest, blow-holes on the top of the head near the 

 middle, separate, but covered with a common flap or valve. 

 Dorsal fin high and falcate. 



Family. — DELPHtNiD^E. 



Head moderate — Both jaws furnished with teeth, which are 

 frequently shed at an early age. Blow-holes united, forming a 

 transverse semi-lunar opening on the top of the head. 



Genus. — Ziphius. 



Jaws tapering, upper jaw toothless, lower with two large, com- 

 pressed teeth. Throat furnished with two diverging furrows. 

 Lower jaw broad. Dorsal tin. 



Genus. — Monodon . 



Few and early deciduous teeth in both jaws. Forehead convex. 

 Upper jaw of male with one or two long, projecting teeth, spirally 

 twisted. Dorsal fin. 



Genus. — Beluga. 



Both jaws with conical, deciduous teeth. Head rounded. No 

 dorsal fin. 



Genus. — PhocEena. 



Both jaws with compressed and permanent teeth. Dorsal fin 

 triangular, and placed in the middle of the back. 



Genus. — Del p uinus. 



Head beaked, and rather convex in front. Dorsal fin fulcate in 

 centre of back. Teeth many, small and conical. 



Sub-order.— SIRENIA. 



Body hairy. Muzzle with bristles. Two nostrils at extremity 

 of snout. Fore-limbs like arms, hinder like fin or tail. 



Genus. — Manatus. 



1—1 



C. <t° M . ?=? = 34. 



0—0 8—8 



Teeth.— I. 



0—0 



Tail or caudal tin rounded and oblong. 



In adults the incisors are wanting, and in the young animal they 



are very small. 



Genus. — Halicore. 

 0—0 „ 5—5 

 5^5 

 Tail or caudal fin semi-lunar. Incisors are large in adults. 



Teeth.— I. — c. - 



0—0 0-0 



Genus. — Rhythia. 



Teeth none, the jaws being furnished in their stead with a 

 horny plate. Tail semi-lunar. 



Order.— RODENTIA. 



Teeth. — Two, long, curved, sharp-edged, rootless incisors in 

 each jaw. Canines absent. Molars very few, and separated by a 

 wide interval from the incisors. 



Feet furnished with claws. 



Family. — Mtmm^E. 



Teeth. — Lower incisors compressed and pointed. Molars gen- 

 erally six in each jaw. 

 Limbs. — Fore-feet with four toes, hind-feet with five toes. 



Genus. — Mus. 



1—1 1—1 2—2 



Teeth. — I. , P. , M. = 16. Incisors mostly 



1—1 1—1 2—2 



smooth. 



Limbs. — Fore-feet with four toes, and a nailed wart instead of a 

 thumb. Hind-feet with five toes. 

 Habitat. — All lands. 



Genus. — Cricetus. 



Teeth. — Incisors smooth, lower compressed. Molars with 

 tubercles. 

 Head. — Ears rounded. Cheek-pouches 

 Limbs. — Feet as in Mus. " 

 Tail. — Very short, and covered with hair. 

 Habitat. — Northern Europe. , ■ 



