192 1.] S. L. HoRA : Fishes of (lie gciiiis Garra. 645 



(iii) The articular and dentary bones on each side have fused 

 to form a single piece, but those of the two sides are distinctly 

 separate. 



(iv) The preopercular bones meet or slightly overlap just 

 behind the lower jaw, presenting an articular sru-face anteriorly. 



(v) The branchiostegeal rays are concealed unrler the oper- 

 cular borders anteriorly and are not visible for a considerable dis- 

 tance behind the mouth. 



(vi) The mouth points anteriorly and is considerably nearer 

 to the dorsal than to the ventral profile of tlie fish. 



From the points enumerated above it is clear that Labeo re- 

 presents a skeletal structure of the mouth])arts, which is at a low 

 stage of organisation ; but at the same time we must remember 

 that in Labeo the mouth is suctorial and this probably accounts 

 for the mobility of its component parts. 



Now let us examine more closely the condition found in a spe- 

 cialised member of the sjenus Garra (fig. 2, i, la). The sutures 

 between the various bones are absent and the skeleton presents 

 a solid structure. The month having been shifted backwards, the 

 maxillae and the premaxillae are well developed and are fairly broad. 

 The backwardly directed process of the posterior jaw (corresponding 

 to the articular bone, etc., of other bony fishes) is short and curved 

 instead of being straight as in Labeo ; those of the two sides are 

 widely separated and articulate with the quadrate of each side 

 respectively. The basihyal is very prominent in the middle behind 

 the lower jaw and is distinctly separate from other structures 

 throughout its length posteriorly. Anteriorly it is flattened out 

 laterally on the dorsal ^urface and to this are attached the anteri- 

 or ends of the branchiostegal raj's which are greatly reduced and 

 are represented by two or three short bony elements. The rays 

 of the two sides are widely separated in the middle. On account 

 of the position of the mouth, Ijoth the jaws ha^-e to be accommo- 

 dated in a short space. 



In a less specialised form of the same genus (fig. 2, 2, la) the 

 fusion of the bony elements is not complete and the position of the 

 mouth near the tip of the snout considerably alters the whole 

 arrangement. The jugal is visible as a separate bone and a faint 

 line of demarcation can be made out between the dentary and the 

 articular bones. The articular is almost straight and meets the 

 opercular border behind ; it is visible on the ventral surface. 

 The basihyal is seen as a rounded process behind the posterior 

 jaw, but is covered for a greater part of its length by the branchi- 

 ostegal rays, which are but slightly reduced. The rays of the 

 two sides meet for a con.siderable distance on the ventral surface. 



The structure met with in Cirrhina (fig. 2, 3, 3a) is not very 

 different from that described above, the only difference being that 

 more of the opercular elements are visible on the under surface, 

 the visible portion of the basihyal is further reduced and the 

 branchiostegal raj's and the articular bones have become more 

 marked. 



