358 CETACEA. 



Genus Orcella, Gray. 

 * Orcella fluminalis, Andr. Plate XXV ■^. 



Dolphin of the Irawady, Andr., Proc. Zool. Soc. 1870, p. 220 et p. 544. 



Orcella fluminalis, kviAx. 1871, Proc. Zool. Soc, pp. 143-4, fig. % ; Blyth, Journ. As. Soc, vol. xliv. 

 ex. no., 1875, p. 34. 



The specimens wMch form tlie subject of this Memoir belong to the male 

 sex. The first was found in a partially decayed condition by Captain Bowers on 

 a sandbank at Bhamo. Decomposition, however, had not progressed so far as 

 to render the skui unfit for preservation. He therefore had the carcass preserved 

 in a mixtu^re of spirit, salt, and arsenic, and had it forwarded to Calcutta, 

 a distance of nearly 2,000 miles. When it reached its destination the skin was 

 intact, although the epidermis had peeled off, but the muscles and viscera 

 were much decayed; still I was enabled to take the followiiig measurements of 

 the specimen and to draw up a brief description of its external characters. 



The general form, so far as I could make out from this then unique example, 

 was the same as that of O. brevirostris, Owen. The fresher specimens afterwards 

 obtained enabled me to determine that the species differs from O. brevirostris in its 

 rather smaller, lower, and more falcate dorsal fin, its more pointed and less anteriorly 

 bulging head, and rather shorter and broader pectoral fins : the colour in both is 

 much alike, being pale slaty above and whitish on the under parts,' but the skin of 

 0. fimninalis is streaked somewhat as in Bisso's dolphin.'^ 



Measurements of the first male, Orcella Jluminalis, obtained by Captain Bowers. 



Inclies. 



From tip of snout to fork of tail along the side 90'00 



„ „ „ to dorsal fin following back curve , . . . . . . . 55'75 



Length of the dorsal fin ............. 475 



Tip of snout to base of pectoral flipper 18'75 



Length of pectoral flipper along anterior margin 17'00 



„ !, „ „ posterior „ 11-75 



Caudal flipper along its anterior margin 13'00 



Snout to the blow-hole on the forehead .......... lO'OO 



Transverse diameter of the blow-hole ........... 1 '50 



Snout to anterior margin of genital slit 52'75 



Length of the external genital orifice ........... 1'75 



Distance between genital slit and nipples .......... 5'00 



Nipples apart from each other ............ 0'75 



Distance between the nipple and anus ........... 2'60 



Length of the gape 5-75 



Snout to anterior angle of eye ............ S'OO 



Longitudinal diameter of the eye 75 



Prom the eye to the ear-hole . 3'76 



Diameter of the external aural orifice 0'12 



Girth over the blow-hole 28 '25 



> In the Proc. Zool. Soc. Lond. 1871, p. 144, I stated on the authority of Captain Bowers that the colour was uni- 

 form dirty white, but repeated views of these dolphins in my late journey up the Irawady convince me that the colours 

 "mentioned above are those natural to it. 



2 Flower, Trans. Zool. Soc, vol. viii, 1872, p. 3. 



