1893.] NATURAL SCIENCES OF PHILADELPHIA. 97 



The posterior trunk gives off the greatest number of these inter- 

 radial vessels. The auterior main trunk gives off four inter-radial 

 vessels. The marginal lobes are highly vascular, although not so 

 wide nor so long as those of the caudal fin. 



The aual fin receives its vascular supply through four sets of 

 large trunks coming off from the inferior aspect of the caudal vein 

 and aorta. These trunks pass nearly straight downward toward 

 the margin of the anal, their distal portions only being slightly tor- 

 tuous. The posterior or fourth trunk, as are all the others, is bifur- 

 cated at the base of the anal into an anterior and posterior branch 

 much in the same way as the similar vessels divide in the dorsal. 

 The fourth trunk gives off the greatest number of inter-radial ves- 

 sels. The second and third give off a smaller number of such 

 inter-radial branches. The first anal trunk appears to supply a 

 portion of the inter-radial spaces at the anterior edge of the anal 

 fin while branches more or less intimately associated with it, or 

 derived from it, pass to the greatly hypertrophied hind-gut. At any 

 rate the vascular supply of this curiously hypertrophied part of the 

 alimentary tract is given off close to this vessel. 



In whatever way the blood passes through the walls of the hind 

 gut H. G. ; it finds its way at last to a large vascular trunk marked 

 S, lying on the ventro-anterior face of H. G. This large vessel S 

 is evidently the homologue of the sub-intestinal vein in other fishes. 

 At the anterior end of S large trunks diverge from it, pass around 

 the mid gut and find their way into the liver. These trunks repre- 

 sent the portal system. Little that is noteworthy can be made out 

 from a transparent view in regard to the way in which the blood 

 reaches the heart from the jugulars. Sections indicate that the 

 Cuvierian ducts are very spacious, more so than is represented in 

 the diagram. 



The ventricle of the heart H is well developed with thick muscu- 

 lar walls. The bulbus arteriosus is a simple thickened muscular 

 tube extending forward from H. The homologies and relations of 

 a large trunk ascending obliquely forward and upward, then bend- 

 ing downward and forward, probably meeting its fellow of the 

 opposite side before it traverses the median face of the mid brain is 

 difficult to determine. A smaller trunk descends from the region 

 over the body toward the eye and probably joins the ophthalmic 

 vessels in that region to finally empty into the basilars and jugulars 

 which pass backward toward the origin of the Cuvierian ducts. 



