Chap. III.] GENERAL ANATOMY. 35 



(inferior jugular, i. /.) from the lower parts of the head. The 

 left ductus is seen in Fig. 14 to receive a factor (spermatic) from 

 the male organs of generation. 



The blood from the stomach and intestines is delivered to the 

 liver by a portal system of veins. There it breaks up into a 

 capillary plexus, and is collected again into the hepatic veins 

 which pass straight to the heart. There is a connecting branch 

 between the portal system and the caudal vein. 



4. The Urino- genital System. The renal organ (13, ren.) is an 

 elongated body lying behind the dorsal wall of the air-bladder. 

 Its anterior enlargement, the head-kidney (h. k.) lies above 

 the coiled caecum of the air-bladder ; its posterior enlargement 

 lies within the anterior portion of the hasmal canal; between 

 the two there is on each side an irregular longitudinal band. 

 From the posterior mass an unpaired ureter passes down to the 

 urinary aperture (u.). 



The testes of the male (soft roe) are elongated lobular bodies, 

 uniting together in the median line for the posterior quarter 

 of their length, and sending off to the genital aperture a common 

 duct. 



The ovaries of the female are somewhat conical pink bodies (hard 

 roe), which also unite with each other posteriorly, and send off a 

 common oviduct to the genital aperture (g.). The ovaries are 

 hollow, and the ova are, when ripe, shed into their cavities and 

 pass out by the oviduct without entering the peritoneal cavity. 



5. The Nervous System. The brain may be exposed by skin- 

 ning the top of the head, removing the muscles, and then break- 

 ing away the roof of the skull. It lies somewhat loosely in the 

 cranial cavity. In it the three divisions may readily be made 

 out. The cerebral hemispheres of the fore-brain are relatively 

 shorter than in the frog. In front of them the large optic 

 nerves form a X, and above them lie the long peduncles of the 

 olfactory lobes. The optic lobes of the mid-brain resemble those 

 of the frog. But the cerebellum of the hind-brain is much 

 larger than in the frog. The medulla oblongata passes almost 

 insensibly into the spinal chord. At the base of the brain are 

 two bean-shaped inferior lobes. 



