PHYLUM CHORDATA 



391 



rectum, from which it receives tributaries, joins the portal vein. 

 The abdominal vein of Amphibians and Reptiles appears to be 

 represented, in part at least, by the epigastric vein (<'])</.), which 

 returns the blood, not from the ventral body-wall, but from the 

 great omentum, a fold of peritoneum, loaded with fat, lying ventral 

 to the intestine and gizzard : the epigastric discharges into the 

 hepatic vein. 



The red blood-corpuscles are oval and nucleated. The tem- 

 perature of the blood is unusually high over 38 C. (100 F.). 



Nervous System. The brain (Fig. 1056) completely fills the 

 cranial cavity, and is remarkable for its short, broad, rounded 



O.I 



'If 



U 



o.t 



FIG. 1056. Columba livia. The brain. A, from above ; B, from below ; C, from the left 

 side. cb. cerebellum ; c. h. cerebral hemispheres ; /. flocculus ; inf. infumlibulum ; m.o. 

 medulla oblongata ; o. /. optic lobes; olf. olfactory bulbs: o.t. optic tracts; pn. pineal 

 body ; II XII, cerebral nerves ; sp. 1, first spinal nerve. (From Parker's Zootomy.) 



form. The medulla oblongata (m. o.) has a well-marked ventral 

 flexure, as in the Lizard. The cerebellum (cb.) is of great size, 

 and has a large median portion and two small lateral lobes or 

 fiocculi (/.) ; the surface of the middle lobe is marked by grooves 

 passing inwards in a radiating manner and carrying with them 

 the grey matter, the extent of which is thus greatly increased. 

 The metaccele (Fig. 1057, v i .) is completely hidden by the cerebellum, 



B B 2 



