240 FISH. [Vol. X. 



pair is given off to supply the hypophysis. The spinal artery 

 sends oif branches, at intervals, which supply the ventral and 

 lateral aspects of the myel. Most of the capillary loops here 

 penetrate the substance from the sides, few from the dorsal or 

 ventral surfaces. 



Concerning the venous system, Schobl finds one paired and 

 two unpaired venous plexuses. The supraplexus is one of the 

 latter, and lies between the hemicerebrums, forming, in part, 

 the roof of the diaccele. Three veins usually join the plexus 

 at its cephalic angle; the middle one of the three is derived 

 from the pia of the cerebrum, while the two lateral ones convey 

 the blood from the lateral, wide-meshed, venous nets interlacing 

 the dura with the plexus. From the caudal angles of the 

 supraplexus there goes out on each side, around the caudal ends 

 of the cerebrum, a vein which connects the supraplexus with 

 the paired lateral plexuses lying on either side of the mesen- 

 cephal. The lateral plexuses receive their blood from the 

 supraplexus and from a lateral vein which, with its fellow, 

 forms a loop around the margin of the cerebrum. In the region 

 of the cerebellum they continue as the jugular veins. The 

 metaplexus covers the cerebellum and metacoele; it receives 

 its blood from the region of the myel, and sends it into the 

 jugular veins. 



There are no plexuses on the ventral aspect. A longitudinal 

 vein, lying between the hemicerebrums, passes caudad, and, in 

 the region of the mesencephal, divides to form an irregular 

 circle, or pentagon, from the iatero-caudal angle of which a 

 vein connects on each side with the lateral plexus. There is 

 found quite constantly, just caudad of the hypophysis, a trans- 

 verse vein connecting the two lateral plexuses. The small 

 venous branches of the cephalic portion of the myel collect 

 into two lateral trunks, and empty into the metaplexus. 

 Farther caudad, these branches unite to form the spinal vein, 

 which passes caudad along the dorsal surface of the myel. 



Rex (43), besides a few minor details, criticizes Schobl's 

 account on the ground that it deals more with the surface 

 circulation, and that the figures are schematic. 



