36 WILLIAM F. ALLEN 



two valves: but in no other series or in any other section in this 

 series or in any dissection of Scorpsenichthys was any direct open- 

 ing found. As stated in the text the filling of the blood vessels 

 from an injection of the longitudinal neural trunk and conversely 

 the filling the lymphatics from an injection of the caudal artery 

 or vein was attributed to the rupturing of the delicate walls sepa- 

 rating these systems, resulting in the extravasation of the injec- 

 tion mass from one system to the other, rather than to a direct 

 passage from one to the other through an open communication. 



Since no caudal connection was established between these sys- 

 tems, and the fact that all the longitudinal trunks increase in cali- 

 ber anteriorly, the flow of lymph must be cephalad to enter the 

 jugular vein after the manner described in an earlier paper. Two 

 forces evidently contribute to propel the lymph forward; one is 

 the difference of pressure between these two systems, forming 

 a sort of suction in the lymphatics; while the other, which is prob- 

 ably the main factor, is the lateral movement of the tail and body 

 against the great wall of water, which presses the lymphatic trunks 

 against the muscles and the bones. 



In these Cottids the profundus longitudinal lymphatic trunks 

 are larger and more important than the subcutaneous trunks. 

 The longitudinal neural trunk is without doubt the main 

 lymphatic conduit of the body. 



Both the longitudinal neural and the longitudinal haemal 

 trunks begin at the last vertebra, the former from the anastomosis 

 of the profundus portions of the lateral trunks, and the latter as 

 a continuation of the caudal trunk. Each receives from between 

 every two segments, a neural or a haemal branch after the manner 

 previously described. 



Two of these, the posterior neural and the posterior ha-mal 

 lymphatic trunks are of enormous caliber. They are formed by 

 the anastomosis of the small dorsal and the large dorsal caudal 

 fin lymphatic trunks, and the small ventral and the large ventral 

 caudal fin lymphatic trunks respectively. 



With the Cottids the dorsal and ventral caudal fin lympnatic 

 trunks are enormous canals which occupy a greater part of the 

 basal canal of the caudal fin. From the dorsal and ventral sur- 



