60 ALLEN 



course lies between the neural spines and anastomose dorsad 

 with the dorsal or the 2 lateral dorsal lymphatic trunks. Since 

 there is no special anterior connection of the dorsal lymphatic 

 trunk with cephalic or pericardial sinus in Scorpcenichthys save 

 through the neural or interspinal and the dorsal intermuscular 

 or transverse vessels into the lateral or myelon trunks, and since 

 the neural or interspinal vessels are much the larger, especially 

 at the junction with the myelonal trunk, it is more than likely 

 that they convey most of the lymph from the anterior portion of 

 the dorsal fin region, while the main supply for the dorsal inter- 

 muscular vessels evidently comes from the surface of the myo- 

 tomes and the surrounding connective tissue. The main mye- 

 lonal trunk extends from the last caudal vertebra to the skull. 

 Its posterior connection with the caudal vein will be described 

 in a later paper. When the skull is reached it bifurcates, each 

 fork after passing laterad between the skull and the first vertebra 

 or atlas empties into a rather large sinus situated at the side of 

 the atlas, directly in front and a little below the base of the first 

 rib. This sinus is designated as the occipital sinus (Figs. 4 

 and 5, Oc.S.) and receives, as has already been stated, the main 

 lateral lymphatic trunk from the side and rear. Very likely 

 this sinus should be considered nothing more than a swelling 

 caused by the union of these 2 important trunks the resultant of 

 which is the cranial lymphatic trunk. 



The course of this sinus-like vessel (Figs. 4 and 5, Cr.L. V.) 

 is along the lateral base of the skull. Following the upper sur- 

 face of the head kidney for a short distance, it crosses under 

 the first spinal nerve and receives from above the Jirst neural or 

 interspinal lymphatic vessel (Figs. 4 and 5, Neu.L. V. {1 ^) ; then 

 continuing along the side of the cranial wall between the great 

 abdominal lymphatic sinus and the IX and X cranial nerves 

 expands into a sinus (Figs. 4 and 5, S.), which lies directly 

 above the jugular vein, on a level with the optic lobes, immedi- 

 ately behind the prootic process and between the skull and the 

 first internal branchial levator muscle. This sinus has 2 open- 

 ings ; the most cephalic one is simply a tapering down of the 

 sinus into a papilla, which curves outward and downward to 

 communicate with the abdominal sinus ; while the other opening 



