ALLEN 



found for Amia or from Scorpcenichthys. Instead of bifurcating 

 behind the skull arid each fork terminating in the cephalic sinus 

 as one might expect, this canal when not far from the posterior 

 end of the skull passes ventrad along the left side of the con- 

 nective tissue separating the two great lateral muscles, and when 

 the vertebral column is reached it bears off obliquely laterad to 

 cross below the exoccipital portion of the skull and terminates in 

 the anterior part of the left branchial sinus (Figs. 8, n and 12, 

 Br.S.) from the inner side. In every specimen of L. tristcechus 

 and in several of L. osseus the ventral lymphatic trunk (Figs. 8 

 and 13, V.L. T.) forked at the level of the base of the pectoral 

 fins, and each of these branches, which immediately become 

 sinus-like, continues parallel until the level of the bulbus arte- 

 riosus is reached, when they bear off at right angles to pass be- 

 tween the clavicle and pericardium and culminate in the corre- 

 sponding pericardial sinuses (Figs. 8 and 13, Per.S.). In that 

 part of their course which lies between the pectorals and the 

 heart they are separated only by a sheath of tough connective 

 tissue, in which there are at least two connecting orifices. With 

 an equal number of L. osseus, as shown in Figs. 14, 15 and 16, 

 the ventral trunk did not fork in the region of the pectorals, but 

 continued cephalad as a single trunk, and when the heart was 

 reached it joined the right pericardial sinus. 



As represented in Figs. 14, 15 and 16 the ventral lymphatic 

 trunk is accompanied by a ventral vein (V. V.), which passes 

 to the left of the heart to discharge itself (Fig. 15) in the left 

 precava a little laterad of the orifice of the hepatic vein. Two 

 ventral arteries (Figs. 14 and 16, V.A.) also accompanied the 

 lymphatic trunk for a short distance. 



Numerous intermuscular lymphatic vessels (Figs. 8 and n, 

 Intm.L. V.) were given off from either side of the dorsal trunk, 

 or from above and below in case of the lateral trunk. These 

 vessels traversed superficially on the septa between the myo- 

 tomes. They doubtless connected the lateral with the dorsal 

 and ventral trunks as in Scorphcenichthys and other fishes, but 

 this fact was not established for a certainty in Lepisosteus. 



Pericardial Sinuses. Each of these sinuses in Lepisosteus 

 (Figs. 8-14, Per.S.) occupies a like position to a similar sinus 



