194 



THE ELASMOBRANCH FISHES 



a similar vertebromuscular branch downward to supply the segment at the 

 sides of the haemal arch. Branches from this ventral artery supply the ventral 

 muscles in the caudal region. From the ventral branch of the vertebromuscu- 

 laris, the anal fin, where such is present, and the ventral lobe of the caudal fin 



Vs.a 



a.sp. V.I. 



Fig. 181. Arteries and veins of the spinal cord, Acanthias. (From Sterzi.) 



a.sp., arteria spinalis; d.r., ramus dorsalis artery; d.r.v., dorsal ramus vein; tr.l., tractus 

 lateralis; v.l., vena limitans; v.r., ramus ventralis artery; v.r.v., ventral ramus vein; vs.a., 

 vertebrospinal artery; vs.v., vertebrospinal vein. 



are supplied with arterial blood. The ventral branches in the region of the fins 

 are better developed than are those of the dorsal series. In a type like Squatina 

 where a dorsal fin is located on the tail the dorsal branches similarly supply 

 this fin as well as the dorsal lobe of the caudal fin. 



