358 CETACEA.
Genus O r c e l l a , Gray.
* O r c e l l a f l t jm in a l i s , Andr. Plate XXYA.
Dolphin of the Irawady, Andr., Proe. Zool. Soe. 1870, p. SJ&'O e t p. 544.
Orcella, Jluminalis, Andr. 1871, Proc. Zool. Soc., pp. 148-4, fig. 2 ; Blyth, Journ. As. Soc., vol. xliv.
ex. no., 1875, p. 84.
The specimens which form the 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 Bhamd. Decomposition, however, had not progressed so far as
to render the skin unfit for preservation. He therefore had the carcass preserved
in a mixture 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 following 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 0. 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,1 but the skin of
O. fi/u/minalis is streaked somewhat as in Basso’s dolphin.8
Measurements of the first male, Orcella fiuminalis, obtained by Captain Bowers.
From tip of snout to fork of tail along the side . 90:00
» » , » to dorsal fin following back curve . . . . . . . . 55*75
Length o f the dorsal fin . . . . . . . . . . . . . 4*75
.Tip o f snout to base of pectoral flipper....................................................................................................... 18'76
Length of pectoral flipper along anterior m a rg in ....................................................................................17*00
» p ‘ » >, posterior „ . . . . • . . . 11*75
Caudal flipper along its anterior margin . 13*00
Snout to the blow-hole on the forehead .. , . , . . . . . 10*00
Transverse diameter of the blow-hole . . . . . . . . . . . . 1*60
Snout to anterior margin of genital s lit ......................................................52*75
Length of the external genital o r if ic e ......................................................................................................... 1*75
Distance between genital slit and nipples ........................................................5*00
Nipples apart from each other . ' 0*75
Distance between the nipple and anus ................................................................................................2*50
Length of the g a p e ............................................................................................................... , . 5*75
Snout to anterior angle of e y e ........................................................... 8*00
Longitudinal diameter of the e y e ......................................... * . . . . . 0*75
From the eye to the e a r - h o l e ................................................................................................................... 3*75
Diameter of the external aural o r ific e ......................................................................................................... 0*12
Girth over the blow-hole . . . . . . . 28*25
1 In the Proc. Zool. Soc. Lond. 1871, p. 144,1 stated on the authority of Captain Bowers that the colour was uniform
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.