LYMPHATICS IN TAIL REGION, SCORPiENICHTHYS 37 



faces of each ray they collect a caudal ray lymphatic vessel. In 

 the median line, between the two hypural bones, at the base of 

 the fin the two caudal fin lymphatic trunks unite in the small 

 posterior caudal sinus. 



This sinus is partially paired in Clinocottus. With Clinocottus 

 and Ophiodon it has conspicuous connections with the posterior 

 portion of the lateral trunks, but in Scorpainichthys there are no 

 such communicacions. Anteriorly two or more caudal lymphatic 

 trunks leave this sinus to foUow the caudal artery into the haemal 

 canal, where they anastomose and form the longitudinal haemal 

 trunk. 



The dorsal and the ventral lymphatic trunks in the caudal 

 region are very inconspicuous vessels in comparison to what they 

 are cephalad or to what they are in the caudal region of other 

 fishes. The tract usually drained by these vessels in the posterior 

 dorsal and the anal fins is collected in Scorpsenichthys by 

 branches of the neural and haemal trunks. In the case of Scor 

 psenichthys the dorsal and ventral trunks of the caudal region may 

 be said to have their origin from the posterior ends of the second 

 dorsal and the anal fins, and after traversing the dorsal and ven- 

 tral median septa of the caudal peduncle they anastomose with 

 the dorsal and the ventral caudal fin lymphatic trunks, which 

 culminate in the longitudinal neural and the longitudinal haemal 

 lymphatic trunks. 



In the tail region the lateral lymphatic trunks are far more 

 important canals than either the dorsal or the ventral. Each 

 can be divided into a main portion, a posterior portion, and a 

 profundus portion. 



The main portion travels immediately beneath the lateral line, 

 in a tough connective sheath that binds the two halves of the lat- 

 eral muscle together. It receives a dorsal and a ventral intermus- 

 cular or transverse lymphatic canal from the surface of each inter- 

 muscular sepum. 



The posterior portion of the lateral trunk is confined to the 

 subcutaneous region between the last vertebra and the base of 

 the caudal fin. It collects a network from the fascia and several 

 from the intrinsic muscles of the caudal fin. With Ophiodon 



