106 MR. W. H. FLOWER ON THE OSTEOLOGY OF 
compared with the forearm, and in the absence of the olecranon process. In the 
carpus, to judge by Eschricht’s figure, some differences of detail may be found. They 
agree in the comparative length and slenderness of the phalanges and spread of the 
fingers; but Platanista differs from Inia and all the other Dolphins in the nearly 
equal development of the four outer digits, giving the remarkable truncated form to 
the termination of the extremity. 
The pelvic bones have unfortunately not been preserved with the skeleton. They 
are also unknown in Platanista. 
II. On the Skull of Pontoporia blainvillii. 
In the Museum at the Jardin des Plantes, Paris, is the skull of a small Dolphin 
brought by M. de Fréminville, an officer in the French navy, from the neighbourhood 
of Monte Video, at the mouth of the Rio de la Plata. This was first described by 
Professor P. Gervais, in the ‘ Bullet. de la Soc. Philomathique de Paris,’ 1844, (27 Avril) 
p- 38, as Delphinus Blainvillei ; also in ‘1Tnstitut,’ of the same year. 
In the part of the ‘Zoology of the Voyage of the Erebus and Terror’ devoted to 
the Cetacea, published in 1846, Dr. Gray gave a figure and brief description of this 
skull, and constituted the genus Pontoporia for the reception of the animal to which it 
belonged. 
Professor Gervais, in the description of the ‘“‘Mammiféres” of d’Orbigny’s ‘ Voyage 
en Amérique Méridionale, published in 1847, but the introduction to which bears the 
date of December 1846, redescribed and figured the skull (plate 23), pointing out 
that its peculiarities were sufficient to entitle it to rank as a subgenus, for which the 
name of Stenodelphis was proposed. In the same plate a figure is given of a long- 
beaked Dolphin, observed by d’Orbigny off the coast of Patagonia, but of which no 
portion was brought home; and a conjecture is thrown out that this Dolphin belonged 
to the same species as the skull presented to the Museum by M. de Fréminville. 
Although this is a mere assumption, and not a very well founded one, as even the 
colour does not correspond with the brief description given by M. de Fréminville*, it 
has unfortunately been treated as a certainty in most systematic works}, and thus Pon- 
toporia, the skull of which shows such near affinities with those of the river-Dolphins 
Inia and Platanista, and which from its only known habitat may be wholly or partially 
fluviatile, and of which the external form is entirely unknown, is now regularly installed 
in zoological literature as an oceanic Dolphin with a high falcate dorsal fin! 
A few weeks ago, and after the whole of the foregoing description of the skeleton of 
* «aprés un renseignement favori par M. de Fréminville, le Dauphin dont provient ce crane, est long de 
quatre pieds, et il est blanc, avec une bande dorsale noire.” 
t See Gervais, Hist. Nat. des Mammiféres (1855), vol. ii. p. 822; Gray, Cat. Seals and Whales, Brit. Mus. 
(1866) p. 231. 
