66 Records of the Indian Mit.seuin. [Vol. XIV, 



short distance along the upper edge of the hypural bone, and is devoid 

 of a spine. 



Two large hypural bones are present, fused at their bases and firmly 

 attached to, or even fused with, the last centrum ; the last {i.e., the 

 upper) hypural is the larger and bears four jointed fin-rays, while the 

 ventral hypural bears three. None of the fin-rays bifurcate, but extend 

 as simple rays to the edge of the fin fold. 



The courses of the spinal cord and the caudal blood vessels are indi- 

 cated in the figure by dotted lines. 



It will be seen that this caudal fin is a wholly ventral structure, since all 

 the supports are ventral to the spinal cord. In the majority of Teleosts, 

 a few dorsal elements enter into the caudal fin, but in Chaudhuria all 

 such elements have been eliminated ; this is a definitely specialized 

 character. The separate caudal fin itself also suggests a specialization 

 above the average eel, and it is probable that the tail is a more definitely 

 propulsive organ than in other Apodes where progression is by a wriggling 

 motion after the fashion of the primitive fishes. 



