230 DR. H. BURMEISTER ON A NEW PORPOISE. ([Feb. 28, 
The underside of the body is somewhat more curved and extended 
than the upper side, and the tail more descending. 
The anus is situated under the beginning of the dorsal fin, 70 centim. 
distant from the notch of the tail-fin. 
The individual seems to be a very young one, because all vestiges 
of genital organs are wanting in the exterior. The anus has a dozen 
radial folds, of which the largest, 6 centim. long, runs forwards; all 
are very deep, and transversely ridged. 
The pectoral fin is faleated, 26 centim. long and 10 broad. At 
its proximal end there are many fine ridges in the skin, and in the 
middle part are ridges indicating the finger-bones beneath. 
The skull proves that the animal is a very young one, and that it 
has come perhaps only to half its natural size; because all the bones are 
very weak, not perfectly ossified, and the vomer entirely cartilaginous. 
It has the general figure of the skull of the European Phocena, dif- 
fering principally in the form of the hinder part of the intermaxil- 
lary bones, which is more abruptly elevated in this new species than 
in the European (see figs. 4 & 5). 
is, 5s gy” 
Side view of the skull of Phocena spinipinnis, reduced one-third. 
The upper jaw has sixteen small teeth, and the lower jaw seventeen, 
on each side, there being no vestige of an alveolar ridge behind them 
in either jaw. The first teeth are smaller and conical, the hinder 
broader and truncated, as seen in figures 3 & 4. This is another cha- 
racter distinguishing it from the European species, the skull of a 
young individual of the latter, which I examined, had twenty-four 
teeth in the upper jaw, and twenty-five in the lower, in both extending 
more towards the hinder part of the jaw than in the new species. 
The specimen of P. spinipinnis which is preserved in the public 
Museum of Buenos Ayres, was captured in the mouth of the River 
