142 MEDICAL ZOOLOGY. 



Pore feet with four toes; hind feet three; these toes terminate in small 

 rounded hoofs, excepting the innermost toe of the hind foot, which is armed 

 with an oblique hooked claw. Tail a mere tubercle. Three mammae on 

 each side ; the anterior is axillary, the two other inguinal. 



Vertebrae. Cervical, 7 ; dorsal, 20-21 ; lumbars, 8 ; caudal, 6. Stomach 

 divided into two chambers ; caecum very large, and colon with numerous dila- 

 tations, with two caecal appendages recalling those of certain birds. (Cu- 

 vier.) The hyrax has close affinities with Rhinoceros. The latter animal 

 differing in being naked, in each foot having three toes, and in the horn-like 

 appendage to nose. 



The hyrax yields hyraceum. Its origin is not certainly known. From 

 analysis, it would appear to be derived from the urine and faeces. 



CATODON (Spermaceti Whale). Nostrils longitudinal, parallel or diverg- 

 ing, covered with a valve, often larger and more developed. Pectoral, broad, 

 truncate. Fingers, 5. Physeteroidia. 



Family 3 Catodontidae. (Head large, subcylindrical, blunt. Lower jaw- 

 narrow. Teeth large, in the lower jaw only, fitting into pits in the gums of 

 the upper one. Nostrils separate, one often abortive. The hinder edge of 

 the maxillary elevated, forming a concavity on the forehead of the skull. 

 Pectoral broad, truncated. Fingers 5. Eye and limb left side smaller; 

 left nostril very large. The lower jaw is early joined in front into a sub- 

 cylindrical mass ; the branches converge and are nearly straight.) 



Catodon. Head rather compressed in the front and truncated, with the 

 blowers close together in the front of the upper edge, separated from the 

 head by an indentation. Nose of skull elongate, broad, depressed. Lower 

 jaw shorter than the upper one, very narrow, cylindrical in front, and the 

 rami united by a symphysis for nearly half its length. Back with a roundish 

 tubercle in front over the eyes, called the 'bunch,' and a rounded ridge of 

 fat behind, highest in front over the genital organs, called the 'hump,' and 

 continued in a ridge to the tail. No true dorsal fin. Pectoral broad, trun- 

 cated. Teeth conical, often worn down. Males larger than females. The 

 atlas is distinct; the other cervical vertebrae are soldered together. (Gray.) 



C. macrocephalus. The northern sperm whale. 



