LYMPHATICS IN TAIL REGION, SCORP^ENICHTHYS 31 



(fig. 4 a, D.R.T.), which traverse the posterior surfaces of the raja's 

 and receive a network from the fin membrane. 



The arrangement of the lymphatics in the posterior dorsal or 

 the posterior portion of the dorsal fin is perceptibly different from 

 the anterior dorsal or the anterior portion of the dorsal fin ; where 

 there were three longitudinal dorsal lymphatic trunks, two of 

 which passed along the sides of the base of the fin and the other 

 traveled through the center of its basal canal. The central 

 trunk received two dorsal spine canals from each spine and com- 

 municated with the lateral trunks through numerous cross bran- 

 ches ; while the lateral dorsal trunks were connected with the longi- 

 tudinal neural trunk through the neural vessels and with the lat- 

 eral trunk through the intermuscular vessels. 



Longitudinal hcemal or inferior vertebral lyjnphatic trunlx. 

 (Figs. 4, 7, and 12, L.Hce.T.). — This great profundus trunk is of 

 almost equal importance to the longitudinal neural lymphatic 

 trunk. In Scorpsenichthys it may be said to take its origin in the 

 haemal canal as a small vessel under the last vertebra, which is 

 continuous with the caudal lymphatic trunk. The latter has 

 been described as traversing the hypural interval, and beside sev- 

 eral minor connections it opens into the posterior caudal sinus 

 at the base of the caudal fin, which also is continuous with the 

 dorsal and ventral caudal fin lymphatic trunks. Under the last 

 vertebra the longitudinal haemal trunk is a ver}^ inconspicuous 

 vessel, and often in sections of Clinocottus through the region of 

 the last vertebra it was invisible. It doubtless receives very little, 

 if any, lymph from the caudal trunk because the resistance in that 

 vessel is evidently less caudad, that is toward the posterior caudal 

 sinus. This being the case a portion of its lymph would ulti- 

 mately reach the longitudinal haemal trunk through the ventral 

 caudal fin trunk, which forms the principal accession to the longi- 

 tudinal haemal, trunk, in fact, it might be said to constitute its 

 source. As stated previousl}^ the ventral caudal fin trunk after 

 leaving the basal canal of the caudal fin, receives the small ven- 

 tral lymphatic trunk, and here separates into two trunks (fig. 4 

 Hce.T. (1) and (2)) which enter the haemal canal opposite the third 

 and fourth vertebrae from the last, and anastomose with the small 



