> 5 8 



CETACEA 



points in common, and do not altogether come under the definition 

 either of the Physeteridce or the Delphi n nice, especially in the 

 important character of the mode of articulation of the ribs with 

 the dorsal vertebrae, the tubercular and capitular articulations, 

 distinct at the commencement of the series, gradually blending 

 together, as they do in most ordinary mammals. The cervical 

 vertebra? are all free. The lachrymal bone is not distinct from the 

 jugal. The jaws are long and narrow, with numerous teeth in 

 both. The symphysis of the mandible exceeds half the length of 

 the whole ramus. Externally the head is divided from the body 

 by a slightly constricted neck. Pectoral limbs broad and truncated. 

 Dorsal fin small or obsolete. Fluviatile or estuarine in habits. 

 There are three distinct genera, which might almost be made the 

 types of families, but it is probably more convenient to keep them 

 together, only regarding them as representing three subfamilies. 



Platanista. 1 — Teeth about %% on each side, set near together, 

 rather large, cylindrical, and sharp-pointed in the young ; in old 

 animals acquiring a large laterally compressed base, which in the 

 posterior part of the series becomes irregularly divided into roots. 

 As the conical enamel-covered crown wears away, the teeth of the 

 young and old animals have a totally different appearance. The 

 rostrum and dentigerous portion of the mandible are so narrow 

 that the teeth of the two sides are almost in contact. Maxillae sup- 

 porting very large, incurved, compressed bony crests, which over- 

 arch the nares and base of the rostrum, and almost meet in the 

 middle line above. Orbits very small and eyes rudimentary, without 

 crystalline lens. External respiratory aperture longitudinal, linear. 

 Vertebra? : C 7, D 10, L 9, C 26 ; total 52. A small caecum. No 

 pelvic bones. Dorsal fin represented by a low ridge. 



One species, P. gangetica, entirely fluviatile, being extensively 

 distributed throughout nearly the whole of the river systems, not 



Fig. SS.— Platanista gangetica. (From Anderson.) 



only of the Ganges, but of the Brahmaputra and Indus, ascending 

 as high as there is water enough to swim in, but never passing out 

 to sea. It is quite blind, and feeds on small fish and crustaceans, 

 groping for them with its long snout in the muddy water at the 

 bottom of the rivers. It attains the length of 8 feet. 2 



J Wagler, Syst. Amphib. etc., p. 35 (1S30). 



- The anatomy of Platanista is fully described by J. Anderson, Zoological 

 Results of Two Expeditions to JFestcm Yunnan, 1878. 



