642 Records of the Indian Mvseum. [Vol. XXII, 



the branchial region. The aiitero-median portion of the posterior 

 lip (h) has become very thin and in its place the anterior border of 

 the disc is coming into prominence. In the branchial region the 

 isthmus is wider, and the raj's much reduced. 



In stage 7 we are approaching the definitive form. The an- 

 terior lip is entirely hidden underneath the labial fold which is 

 now distinctly fringed and tuberculate, and the median portion of 

 the posterior lip is represented by small prominences in front of 

 its posterior swollen region. The connective is well-marked and 

 forms an anterior continuation of the posterior border of the disc 

 on either side. The posterior jaw is now visible in the middle. 

 The branchiostegal membranes no longer meet behind the disc and 

 their rays are greatly reduced. 



In the final stage all traces of the posterior lip are gone ex- 

 cept for the connective {d) near the angle of the mouth ; the mouth 

 is now surrounded by secondary folds both anteriorly and poste- 

 riorly. The isthmus is much wider and the rays in the branchi- 

 ostegal membranes greatly reduced. From this stage it is but a 

 small step to reach the condition found in the adults of the most 

 advanced species. The only change is that the isthmus is still 

 wider and the rays further reduced. 



It will be advantageous at this point to enumerate the lines 

 along which the development of the under surface of head has 

 taken place in Garra: — 



(i) The anterior labial fold develops considerably and ultimate- 

 ly covers the anterior lip. 



(ii) The anterior Hp, though prominent in the younger stages, 

 is much reduced in the older and is covered by the anterior labial 

 fold. 



(iii) The mouth, which at first occupies a position near tiie tiji 

 of the snout, becomes shifted ijackwards and in all the older stages 

 is clearly ventral in position. 



(iv) The posterior lip in younger stages is narrow in the 

 middle, but greatly thickened near the angle of the mouth. Dur- 

 ing the development of the fisli the median part is replaced Ijy a 

 posterior labial fold ; but the thickened portions near the angles 

 separate off and form definite connectives on either side between 

 the upper labial fold and the post.^rior border of the disc. 



(v) The disc begins as a finely papillate squarish area just 

 behind the posterior lip. Its anterior portion is early marked off 

 into the disc proper and the papillae (which are probably the disc 

 rudiments) are pushed backwards. They ultimately vanish and their 

 place is taken by the posterior border of the disc. The anterior 

 liorder of the disc is niarked off as a posterior labial fold having a 

 callous circular portion in the middle. 



(vi) The branchial membranes containing the branchiostegal 

 rays meet for a considerable distance in young individuals, but 

 with the growth of the fish they are widely separated and the 

 rays in them greatly reduced. 



