VII. NOTES ON THE OCCASIONAL AB- 

 SENCE OF THE PAIRED FINS IN 

 FRESH WATER FISHES, WITH SOME 

 OBSERVATIONS ON THE TWO APODAL 

 GENERA CHANNA, GRONOW AND APUA, 

 BL YTH. 



By Sunder Lal Hora. M.Sc, 

 Research Assistant, Zoological Survey of India. 



Willey ' has receutl.v referred to the absence of the ventral 

 fins in a male specimen of Amia calva and urges the necessity of 

 recording such observations as they are likely to throw some light 

 on "natural mutations amongst fishes." In the course of my 

 studies on the freshwater fishes of India, I have come across 

 a few " mutations " of this nature and I take this opportunity of 

 bringing them to notice. 



(i) While examining a large collection of fish made in Manipur 

 by the Manipnr Survey party and myself, I found a specimen of 

 Barilius barila (Ham. Buch.), in which both, the ventral fins were 

 totally absent. The aVjnormal specimen was captured in Khurda 

 stream near Thanga, with a large number of normal specimens. 

 It does not seem to have suffered any disadvantage on account of 

 the absence of the ventrals. There is no external mark or scar to 

 show that the condition is the result of an accident or injury. 

 The proper place of the origin of the ventrals is completely covered 

 with scales. Comparison of the arrangement of the scales in 

 a normal and the abnormal specimen is shown in figure i («). 



Dissection of the body wall in the region of the pelvic fins 

 under a high power of a binocular microscope, by stripping the 

 different layers one by one, revealed no irregularity of arrange- 

 ment and no trace of the pelvic girdle was found. 



The total length of the abnormal specimen including the 

 length of the caudal fin is 94 mm., while the average length of 

 the species is about 125 mm. 



(ii) In the Manipur collection I found another interesting 

 specimen of a new species which I call Barilius dogar singhi , in 

 which the ventral fin of the left side was absent. The place of 

 origin of the ventral fin is here also covered with scales. In a 

 normal specimen there are four scales between the bases of the 

 ventrals. They are longer than the rest and are more pointed 

 posteriorly ; they are arranged in such a way as to form a sheath 

 on the inner side of the bases of the ventrals. In the abnormal 



' W'illev. Pi'oc. Zool. Soc. London, pp. Sg — yo (1920). 



