DISTEIBUTION OF THE SUBCUTANEOUS VESSELS IN THE 

 TAIL EEGION OF LEPISOSTEUS. 



BY 



WILLIAM F. ALLEN. 



From the Hersstein Marine Lahoratory, Pacific Gi'ove, Cal. 



With 25 Figures. 



Introduction. 



The following is merely a continuation of a recent article^ on the 

 distribution of the subcutaneous vessels in the head region of the 

 Ganoids PoJyodon and Lepisosteiis; which was an attempt to see what 

 light a study of these vessels in this group would throw on the general 

 problem as to whether these vessels in fishes are veins or lymphatics; 

 or a conunon system that may function for both; or if perchance they 

 might not function as veins in the lower or more generalized forms and 

 lymphatics in the higher or more specialized forms. In other words, to 

 ascertain, if possible, what bearing, if any, they might have on the 

 origin and phylogeny of the lymj)hatic system. 



Material and Method of Procedure. — Two species of Lepisosteus were 

 studied, namely, L. tristceclius and L. osseus. They were obtained from 

 the Ohio and Mississippi Elvers -about Cairo, Illinois. The tails of 

 these specimens were transversely severed immediately in front of the 

 dorsal and anal fins; and the caudal vein and one of the lateral sub- 

 cutaneous trunks were injected caudad from the cut ends with a 

 Prussian blue gelatin mass. Ordinarily when injecting one of the 

 lateral trunks, the opposite trunk and the dorsal and ventral sub- 

 cutaneous trunks were plugged with cotton. With a few specimens the 

 caudal artery was injected with Hoyer's lead chromate gelatin mass. 

 In making the injections the cut end of the specimen was raised consid- 



'"Distribntion of the Subcutaneous Vessels iu the Head Region of the 

 Ganoids, Poltjodoii and Lepisosteus." Proc. Wasli. Acail. Sci.. Vol. IX, pp. 79- 

 158, 1907. 



American .Tolexal of Anatomy. — Vol. VIII. 



