LYMPHATICS IN TAIL REGION, SCORP^NICHTHYS 33 



At various intervals interlinking lympathic vessels were seen 

 passing around ttie centra, and connecting the longitudinal haemal 

 trunk with the longitudinal neural trunk. 



As regards these longitudinal profundus lymphatic trunks in 

 other fishes, especially inTeleosts, as protrayed by different authors 

 there appears to be great variation. In some species one trunk 

 is said to be absent ; in another, the other ; while in still others both 

 are absent or else have been overlooked. 



In the Selachians there are no longitudinal neural trunks, but 

 in Scyllium, Mustelus, and Squatina, Mayer (p. 320) describes a 

 vasa vasorum in the haemal canal, which consists of a longitudinal 

 vein traveling along between the caudal artery and vein. It is 

 said to receive direct communications from each intercostal or 

 intersegmental artery, and to give off at regular intervals bran- 

 ches to the caudal vein. Favaro finds a similar arrangement in 

 Squalus, where he designates the longitudinal vein running be- 

 tween the caudal artery and vein as the vasa intermedia, the con- 

 necting branches between the segmental or intersegmental arter- 

 ies and the vasa intermedia are termed the arteria segmentalis 

 vasorum intermediorum ; while the connecting vessels between 

 the vasa vasorium and the caudal vein are plainly figured but 

 are not named. In fig. 156 Favaro graphically shows the evolu- 

 tion of the longitudinal haemal trunk of Teleosts from the vasa 

 intermedia of Squalus. The arrangement for Squalus was just 

 given above. With Raja he portrays these connecting arteries 

 as passing caudad a short distance before anastomosing with 

 the vasa intermedia; while the arrangement of the connecting 

 vessels between the vasa intermedia and the caudal vein remain 

 as in Squalus. With Acipenser these connecting arteries are 

 continued caudad a short distance as in Raja, but here they fork, 

 one stem joins the vasa intermedia and the other is continued 

 caudad to anastomose with the following segemental artery, thus 

 forming a continuous longitudinal arterial trunk, designated as 

 the arteria longitudinales vasorium intermediorum (Minor caudal 

 artery of Scorpaenichthys) . The venous connections between 

 the vasa intermedia and the caudal vein are the sam e as in Squal- 

 us and Raja. With the Teleosts the arterial arrangement islden- 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 11, NO. 1. 



