212 Records of the Indian Museum. [Vol. XIX, 



sides of the head. These dots are arranged in a regular row along 

 the middle hne on each side ; below this they become fewer in 

 number and totally disappear from the undersurface of the head 

 and body. The fins are colourless. 



A complete specimen measures 21 mm. in length. The length 

 of the caudal is 45 mm. and that of the head about 4'2 mm. The 

 length of the head is contained 4| times in the total length and 

 about 3J'y times in the length without the caudal. The eyes are 

 situated about the middle of the head and are directed outwards 

 and upwards. 



Locality : — Piphima in the Naga Hills, Assam, at an altitude 

 of 3000 feet. 



The specimens were captured during the month of February, 

 1920. 



The following observations were made in the field by keeping 

 the fish alive in water in a glass tube : — 



The pectoral fins were pressed against the sides of the tube, 

 their undivided rays being in close contact with the glass, while 

 the divided rays were in constant motion. The fish was also 

 observed opening and closing its mouth constantly and sometimes 

 it was seen to dart rapidly from one place to another, probably 

 by the help of its unpaired fins, but the movements were too 

 rapid for detailed analysis in the circumstances. 



The families of Cyprinoidea may be distinguished by the 

 nature of the air-bladder. By most of the older authors the sub- 

 order was divided into three families, which would be distinguished 

 thus : — 



"Air-bladder well-developed, divided into two cham- 

 bers arranged longitudinally and lying free in the 

 abdominal cavity ... . . . . i. Cyprinidae. 



Air-bladder divided into two lateral chambers and 



enclosed by a bony capsule ... ... 2. Cobitidae. 



Air bladder absent ... ... ... 3. Homalopteridae. 



We now know that the Homalopteridae possess an air- 

 bladder which is of the same type as is found in the Cobitidae. 

 But whereas in the Cobitidae the two lateral chambers are still 

 connected by a tube, and sometimes a small process may be 

 present directed backwards from the tube, probably representing the 

 posterior chamber of the t3^pical Cyprinoid fishes ; in the Homa- 

 lopteridae the two lateral chambers show a tendency to separate 

 off from one another and all remains of a posterior chamber are 

 absent. The Homalopteridae are more highly specialized for a life 

 in mountain torrents than the Cobitidae, and probably the further 

 reduction in the air-bladder of the former is due to this adapta- 

 tion. The uniserial nature of the pharyngeal teeth in both of 

 these families points to their close relationship. 



The species of Psilorhynchus show a marked resemblance to 

 those of Homaloptera or Bhavania, but as is abundantly clear 

 fiom dissections the resemblances are only superficial. Life in hill- 



