52 ALLEX 



the injecting mass have certainly been found in Scorpcenichthys, 

 following along superficially in the septa between the myotomes. 

 The ventral vessels anastomose with the ventral lymphatic trunk 

 and the dorsal with the dorsal trunk. These vessels are con- 

 nected by a lymphatic network, which has its origin from the 

 surface of the muscles and connective tissue, and branches are 

 also received that arise from a very rich network on the subcuta- 

 neous layer of the skin. This network is especially conspicuous 

 in fresh-water drum, Aplodinotus grunniens, where it can be seen 

 through the transparent scales. The secondary lateral trunks 

 described by Trois in Uranoscopus are certainly of only secon- 

 dary importance in Scorpcenichthys . For not only is the central 

 vessel much larger and connected at either end with the venous 

 system, but the secondary lateral vessels are only found in the 

 cephalic end of the trunk, and the most dorsal one is not a con- 

 tinuous trunk, but simply a series of regular cross vessels. 



Pectoral sinus and lymphatics of the pectoral Jin. — This 

 sinus (Figs, i, 2, 3, 4, 5 and 6, P.S.) lies directly below the 

 skin between the base of the pectoral fin and the post-clavicle, or 

 perhaps to more accurately state it, between the superficial pec- 

 toral adductor muscle, and the anterior myotomes and the 

 sterno-hyoideus muscle (see fig. 2). In a well-injected speci- 

 men it can be traced cephalad between the sterno-hyoideus and 

 superficial abductor muscles to what has been designated as the 

 ventral pericardial sinus (Figs. 3, 4 and 6, V.Per.S.). Since 

 the ventral pericardial sinus receives the ventral lymphatic trunk, 

 the union of the pectoral sinus with the ventral pericardial sinus 

 is analogous to the union of the ventral intermuscular or trans- 

 verse vessels with the ventral lymphatic trunk. In addition to 

 its dorsal and ventral connections the pectoral sinus is always 

 in direct communication with the abdominal sinus (Figs. 4 and 

 6, Abd.S.) In a very large specimen from which Fig. 6 was 

 drawn an additional connection was also noticed with abdomi- 

 nal sinus, which received a communicating branch from the 

 pericardial sinus. Near the termination of the pectoral sinus 

 in the lateral lymphatic trunk it receives a common trunk formed 

 from the union of the outer and the inner pectoral fin sinuses 

 (see figs. 1, 4 and 6). Of these two sinuses the inner is the 



