LYMPHATICS IN TAIL REGION, SCORP^NICHTHYS 23 



and ventral portion of the fin, two caudal ray lymphatic vessels 

 from adjacent rays would anastomose a short distance from the 

 basal canal of the caudal fin, and the combined trunk would term- 

 inate in the caudal fin lymphatic trunk. Toward the center of 

 the fin, as shown in figs. 5 and 7 where this region was dissected 

 out more carefully than in fig. 4 what at first appeared to be a 

 continuous caudal fin trunk is in reality composed of several diver- 

 ticula into which several of the caudal ray trunks emptied. One 

 of these, as shown in fig. 5, is continued so as to empty directly 

 into the posterior caudal sinus. 



Posterior caudal sinus. (Figs. 3-7, C.S.). — The sinus so named 

 can hardly be compared to the paired caudal sinuses of Lepisos- 

 teus (p. 67 and figs. 1-7, R. a smdL.C.S.) and other fishes, which 

 are situated behind the last vertebra, collect the lymph from the 

 tail region and eject it into the caudal vein, but is evidently 

 homologous to what Favaro (p. 184 and fig. 84) describes and fig- 

 ures as the sinus lymphaticus caudalis in Tinea vulgaris; for in 

 this fish he also describes and figures a paired caudal lymphatic 

 heart situated behind the last vertebra consisting of two cavities, 

 designated as the atrium cordis caudalis and the ventriculus cor- 

 dis caudalis. While these caudal hearts or sinuses as described 

 in Tinea have somewhat different connections than are found in 

 Lepisosteus and other fishes, still they have much in common and 

 must be homologous. In Clinocottus the so-called posterior caudal 

 sinus (fig. 3, C.S.) is partially paired throughout most of its length 

 and each reservoir is in communication with the posterior por- 

 tion of a lateral lymphatic trunk. With Scorpsenichthys most 

 diligent search was made to find a connection between the pos- 

 terior portion of the lateral trunk and the posterior caudal sinus, 

 but none was found. A branch of the caudal artery is given off 

 to the periphery, which should not be confused with the above 

 mentioned lymphatic connection. In the anterior end of the 

 posterior caudal sinus there are at least two orifices into which 

 the caudal lymphatic trunks open. 



These trunks (figs. 4-7, C.T.) are very slender and delicate 

 vessels in Scorpsenichthys, which occupy most of the space be- 

 tween the caudal artery and the hypural bones. Upon reaching 



