LYMPHATICS IN TAIL REGION, SCORP^NICHTHYS 39 



likewise curve around to the side of the centra, where each divides 

 into a lateral vessel which has an identical course to the lateral 

 vessel described above, and a neural vessel which follows the 

 neural spine to the periphery. The third or haemal vessels pursue 

 a ventral course along the haemal spines to the periphery. The 

 outcome of this arrangement is that every two myotomes are 

 supplied by a neural, hsemal, and two lateral arteries and veins. 



Resume. — In connection with this system of canals in the tail 

 region of these two Cottids two views are tenable. One is, that it 

 is a separate lymphatic system, probably more closely related to 

 the blood-vascular system than in the higher Vertebrata; the 

 other is, that it is a separate venous system, which has no counter- 

 part in the arterial system, but which may function also for lym- 

 phatics. 



Of these two views the former seems more plausible for the 

 following reasons. — So far as could be deterpiined in the tail re- 

 gion there w^as no direct connection between this system and the 

 caudal vein as is found in most fishes or with the arterial system 

 in the periphery. The smaller branches usually follow the arteries, 

 often nearly surrounding them, and their networks are decidedly 

 lymphatic in the character of their meshes. The caliber of these 

 trunks are also much larger than one would expect veins to be. 

 When these canals are severed in a living specimen no blood is 

 expelled, in fact, in a series of microscopical sections one frequently 

 has to look at several sections to find a corpuscle in one of these 

 trunks. With a single possible exception the entire tail region, 

 both superficial and deep, are amply supplied with veins that 

 have mutual relations with the arteries ; while the lymphatic sys- 

 tem is always isolated. It was shown that along each neural 

 spine there extended a neural lymphatic vessel, which received 

 lymph from the dorsal fin and the dorsal musculature, but none 

 from the lateral periphery (that region being drained by the 

 lateral lymphatic trunk), and emptied into the longitudinal neural 

 lymphatic trunk. Also along each alternate neural spine there 

 traveled a neural artery, which arose from the caudal artery, and 

 supplied the dorsal and lateral musculature, the dorsal fin and 

 its musculature, and the dorsal and lateral periphery. Likewise 



