| OCR Text |
Show 1871.] FRESHWATER SILUROIDS OF INDIA. 709 The genus Arius is found throughout the seas and estuaries of India, Ceylon, Burmah, the Andaman and Nicobar Islands; it also extends to most of the tropical regions. In India it is strictly marine, but enters rivers often to a long distance from their mouths. Whether it breeds in the fresh waters is questionable. OSTEOGENIOSUS VALENCIENNESII, Bleeker. In a specimen from Moulmein, taken in the river, the air-vessel was large, heart-shaped, having an internal longitudinal septum, and not enclosed in bone. Geographical distribution.-A marine genus, extending through the seas of India to the Malay archipelago. Some enter the mouths of rivers. PANGASIUS BUCHANANI, CUV. et Val. Pimelodus pangasius, H. B. pl. 33. f. 52. Air-vessel large, extensive, and divided into three portions. The anterior is somewhat heart-shaped, considerably the largest, and extends from the commencement of the vertebral column to nearly opposite the posterior extremity of the pectoral fin. Its remaining portions are narrow, compressed, and continued to opposite the middle of the anal fin, amongst the muscles covering the heemal spines. It then becomes narrow and reduplicated on itself for a short distance. On removing the front wall of its first or largest portion, its interior is seen to consist of two pear-shaped cavities, the bases of which are inferior and lateral, whilst they coalesce anteriorly ; the whole of the posterior half of this portion is cellular; and so is the small intermediate space between the two uncelled pyriform portions. The two posterior divisions of the air-vessel have valvular-shaped folds partially subdividing its interior. Geographical distribution.-The Indian species is found within tidal influence, as well as inland in the larger rivers far beyond the tides. The genus extends through Burmah to the Malay archipelago. Genus PSEUDEUTROPIUS, Bleeker. Schilbichthys, sp., Bleeker. Air-vessel in P. garua, H. B., small and somewhat heart-shaped, it is closely attached to the bodies of the anterior vertebrae; its external fibrous covering is of moderate strength. In P. atheri-noides, Bloch, it is of a large size, as wide as the abdominal cavity, and on removing its front wall a longitudinal septum is seen dividing it into lateral portions, which, however, communicate anteriorly. In some there is a further subdivision in its posterior portion. In some of the larger species (as P. murius, H. B., and P. goongwaree, Sykes) the air-vessel is larger than in P. garua, and comparatively considerably smaller than in P. atherinoides, Bloch. P. garua, in which the adipose dorsal is so small, and altogether absorbed in the adult, |
