GO William F. Allen 



bifurcate, each branch extending laterad to join its respective cephalic 

 sinus. At the caudal end Hopkins states that "it anastomoses with the 

 lateral lymph vessel, joining it just after the latter turns at right angles 

 to enter the caudal sinus." Hopkins further believes that the dorsal 

 trunk bifurcates, each fork terminating in a lateral trunk immediately 

 after it bends to join the caudal sinus. This is so represented in 

 Fig. 10, r. 



From the above paragraphs it is evident that the distribution of the 

 dorsal subcutaneous trunk of Lepisosteus most closely resembles Hop- 

 kins' description of a similar trunk for Amiatus. On the contrary, the 

 dorsal trunk never forks caudad or terminates in the lateral trunk, but 

 rather in one of the sinuses (x), each of which is a deep reservoir 

 formed by the union of lateral and haemal trunks which culminates in 

 its respective caudal sinus. As with Amiatus and Pleuronectes, it is a 

 single median trunk in the dorsal fin region. Since there is no longi- 

 tudinal neural trunk in Lepisosteus, there are no neural vessels to com- 

 municate with the dorsal trunk, as is the case with some Teleosts. Later 

 on the lateral trunk will be described as collecting numerous inter- 

 muscular or transverse vessels, which doubtless communicate above with 

 the dorsal trunk as in 8coq)a'nichthys, but this point was not determined 

 for a certainty. In the basal canal of the dorsal fin the dorsal trunk 

 received a canal from the anterior and posterior surfaces of each ray, 

 which collected a network of canals from the fin membrane. These 

 dorsal ray canals were accompanied more proximad by dorsal ray veins, 

 which gathered a venous network from the fin membrane, and ultimately 

 discharged into a dorsal fin vein that emptied into the caudal vein. 

 As previously stated (pp. 7 and 8), this system of veins may be homo- 

 logous to the deep dorsal fin veins of the Selachians, which were de- 

 scribed by Mayer as anastomosing with the dorsal subcutaneous vein in 

 a reservoir at the posterior end of the fin, but with Lepisosteus there 

 was no anastomosis between the venous system and the subcutaneous 

 system. The two systems were distinctly separate. "We have, therefore, 

 in Lepisosteus a more specialized condition than is to be found in the 

 Selachians. It might also be mentioned that these two systems are 

 clearly unconnected in the dorsal fin region among the Teleosts. With 

 ScorpcenicJitliys, however, there is no one vein that collects the entire 

 venous blood from the dorsal fin, but several of the neural veins are 

 extended to the fin and send off branches that traverse the fin rays and 

 receive the capillary network from the fin. 



