This paper deals with the functional morphology of the pelvic girdle and fins in various genera of hill stream cyprinid and sisorid fishes. The pelvic plate of Pseudecheneis shows the greatest modification; it is unusually large and reaches the coracoids of the pectoral arch in front.
The elaborate working of the pelvic muscles and their function in bringing about effective adhesion by the pelvic fins is described in detail. The formation of a new muscle, M. pars retractor ischii of the M. mesioventralis, is reported in Garra and Psilorhynchus (Cyprinidae) and in Glyptothorax and Pseudecheneis (Sisoridae). In Pseudecheneis, the complete separation of this muscle from the M. mesioventral, and modification of the M. protractor ischii, are discussed in relation to the crawling habit of the genus. The appearance of the M. arrector pel vicalis ventralis in Glyptothorax and Pseudecheneis among sisorids has been associated with the adhesive function of the outer ray.