640 COLLEGE ZOOLOGY 



cerebellum is divided into three parts, a central portion (cb f ) 

 and two lateral lobes. 



THE SENSE ORGANS. The eyes of mammals are without 

 a pecten such as is present in birds. The large outer ear, or 

 pinna, serves to collect sound waves; the middle ear transmits 

 the vibrations of the tympanic membrane, or eardrum, by means 

 of three auditory ossicles, which extend across the tympanic 

 cavity, to the inner ear. The cochlea of the inner ear is spirally 



u. 



b.o. 



FIG. 512. Side view of brain of the rabbit, b.o, olfactory bulb; cb', supe- 

 rior vermis of cerebellum; f.b, cerebral hemisphere; h.b, cerebellum; h.l, hippo- 

 campal lobe; m.d, medulla oblongata; p.v, pons Varolii; r.f, rhinal fissure; 

 i-xii, cranial nerves. (From Wiedersheim.) 



coiled, and not simply curved as in the pigeon. The nasal 

 cavities are very large, indicating a highly developed sense of 

 smell. 



THE REPRODUCTIVE SYSTEM. The two testes of the male 

 lie in oval pouches of skin, called scrotal sacs, one on either side of 

 the copulatory organ, or penis. They may be drawn back into 

 the abdominal cavity through the narrow inguinal canals. The 

 spermatozoa pass from the testes into irregular convoluted tubes 

 called the epididymes; they then enter the vasa defer entia which 

 lead into the abdominal cavity and open into a medium sac, 

 the uterus masculinus, attached to the dorsal surface of the urino- 

 genital canal, or urethra. During copulation the spermatozoa 

 pass into the urethra and are transferred to the female by the 

 penis. Surrounding the vasa deferentia is a prostate gland 



