646 Records of the Indian Museum. [Vol. XXII, 



In Crossochilus (fig. 2, 4, 4a) the mouth is situated consider- 

 ably behind the tip of the snout and consequent!}- the structure of 

 the mouth-parts is different from that found in Cirrhina, and in 

 certain respects resembles that of a specialised form of Garra. It 

 may also be pointed out that, like Garra, a fringed, tuberculated, 

 well-developed anterior labial fold is present in Crossochilus. The 

 articular bone is fairly extensive and only a small portion of the 

 basihyal is visible from below. The branchiostegal rays meet for a 

 short distance behind the tip of the basihyal and then suddenly 

 diverge outwards. The rays are reduced. 



AIR-BLADDER AND ASSOCIATED SKELETAL STRUC- 

 TURES. 



Tlie air-bladder has long been considered to be an organ of 

 the greatest importance in the taxonomy of the bony fishes and 

 especially in distinguishing the families of CyiDrinoidea. I have 

 carefully examined this organ in the various species of Garra and 

 also in Labeo rohila, Cirrhina mrigala and Crossochilus laiia. The 

 comparison is instructive. The normal type of bladder is present 

 in Cirrhina (fig. 3, 2) and Labeo (fig. 3, i) and its length is con- 

 tained about 3'3 times in the length of the fish including the 

 caudal fin. The anterior chamber is smaller than the posterior 

 a:id is in the form of a short massive cylinder. The posterior 

 chamber is almost as l:)road as the anterior a short distance behind 

 its commencement, but thence it gradually tapers to the end. In 

 all the less modified species of Garra that I have examined, viz. G. 

 adiscHS.G. rossicus,G. hlanfordi and G. rnjus, the bladder agrees 

 with this type in form and extent, whereas in all specialised species 

 of the genus and in Crossochilus latia it is somewhat modified. 

 The modifications chiefly consist in the form and extent of the 

 posterior chamber, which, instead of being swollen in the middle, 

 may be of uniform thickness throughout, with its walls somewhat 

 thickened. This condition is found in Garra gravelyi, G. jenkinsoni- 

 anum and G. niuUya. In the remaining species the whole of the 

 bladder is greatly reduced and its length is never contained less 

 than 5 times in the length of the fish. The extreme phase of 

 reduction within the genus is reached in Garra stenorliynchus, G. 

 arabica, G. gotyla and G. nasuttis, in which the bladder is contained 

 about 15 times in the length of the fish without the caudal. In 

 G. gotyla, G. nasutus and G. lissorhynchus, the bladder is covered by 

 a thick, fibrous coat and is firmly fixed to the bodj'-wall. In 

 some species the posterior chamber is greatly reduced and its cavitv 

 almost obliterated. 



In Crossochilus (fig. 3, 11) the bladder resembles that of certain 

 species of Garra ; its length is contained 5-3 times in the total length 

 of the fish. The posterior chamber is long but of uniform thickness 

 throughout. 



Having found so much variation in the species of Garra as 

 regards this interesting organ I was almost tempted to regard it 



