THE CAUDAL FIN OF THE EEL CHAUDHURIA. 



(With text-figure.) 



By R. H. Whitehouse, M.Sc. Professor of Zoology, 

 Government CoUe(je, Lahore. 



A special interest attaches to the caudal fin of this peculiar eel ^ since 

 it is discontinuous ; in all other known eels the caudal fin is continuous 

 with the dorsal and anal fins, in \vhich the fin-rays are supported by 

 radials or interspinous bones alternating with the neural and haemal 

 spines. In Chaudhuria, the last fin-rays of the dorsal and anal fins are 

 attached to radials situated between the sixth and seventh vertebral 

 arches counted from the posterior end ; there is thus a considerable 

 space devoid of fin-rays separating the dorsal and anal from the caudal 

 fin. However the fin fold is practically continuous and the last 

 dermotrichia of the dorsal and anal fins reach backvrard as far as the 

 last centrum. 



£h^»£tt fin ,. . 



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S2S>-C<9>^^ 



ray 



nras^g 



The neural and haemal arches of the terminal centra are typical of 

 the Apodes, the neural arch having an extended base with a long back- 

 wardly directed spine. The penultimate centrum has a somewhat 

 reduced neural arch ; this is a feature common not only to the eels but 

 to the majority of the Teleostean fishes, and is probably due to suppres- 

 sion consequent on the upturning of the extremity during the hetero- 

 cercal stage. As regards the spine of this neural arch, I cannot say 

 with certainty whether it is f>resent or not ; the anterior dorsal edge 

 is certainly truncated, which suggests the absence of the spine ; at the 

 same time, there ap'pears to be a very small spine attached to this angle 

 of the arch, but determination by dissection of such a small structure is 

 almost impossible ; the point however is of minor importance. The 

 neural arch of the last centrum is typically elongated, extending some 



1 The genus and its only kn^^yn species (C. caudata) are described by Annandale on 

 pp. 27-28 of this volume. 



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