92 MR. W. H. FLOWER ON THE OSTEOLOGY OF 
broad and -25" high, distinctly separated by a suture from the frontals. It will be seen 
from the above description that the nasals are extremely different from those of most of 
the Delphinide, in which they are generally reduced to irregular, oval, unsymmetrical 
nodules. Phocena, however, differs from its allies in this respect, and closely approxi- 
mates to Inia. In Platanista also the nasal bones are well-developed flattened plates ; 
but they partake of the great elongation, narrowness, and lateral distortion which per- 
vades this region of the skull. 
The opening formed by the junction of the anterior nares is 1” long, and the same 
width posteriorly. It is bounded laterally and in front by two very prominent, rounded, 
longitudinal elevations, formed by a thickening of the premaxillaries, like that seen in 
this region in Phocena and Beluga, but considerably more marked. No part of the 
maxillaries comes to the surface in the middle line in front of the narial aperture as in 
many of the Delphinide (e. g. Globiocephalus). 
The rostrum is exceedingly long and narrow, and, except at its base, much compressed. 
The diminution of its breadth takes place rapidly for the first fourth of its length, but 
for the remaining portion only very gradually. The bone of which it is composed is of 
dense texture; and, even in this young subject, the sutures between the premaxillaries 
and maxillaries are almost obliterated. The width of the premaxillaries scarcely alters 
through their entire length, their outer boundaries being parallel, and the general 
diminution in the breadth of the rostrum taking place solely at the expense of the 
maxillaries. There is a narrow interval throughout in the middle line between the 
premaxillaries, and the subjacent cavity for the median ethmoid cartilage is not filled up 
with bone as in many of the Ziphiine. 
On each side of the inferior surface of the rostrum (Plate XX VI. fig. 1) the alveolar 
tract, marked by the row of deep and distinctly separated tooth-sockets, extends from 
the apex to 12” from the bottom of the antorbital notch. Between these tracts the 
palatine surface is quite flat, and in the anterior three-fourths slightly raised above 
their level. At the middle of the rostrum it is only -4" wide, but gradually expands 
posteriorly. Between the two maxillary bones, in the median line is a narrow fissure, 
in which, 1 behind the middle of the rostrum, a thin strip of the vomer ‘appears, and 
continues visible as far as the posterior edge of the palate. 
The remarkable conformation of the bones of the hinder part of the palatial region 
in the Gangetic Dolphin has been well described by Eschricht, who pointed out that the 
great lamella of bone which continues backwards the palatine portion of the maxillaries, 
and passes outwards and upwards to articulate with the squamosals and frontals, is 
really the pterygoid, and not the palatine as Cuvier supposed*. The easily separable 
condition of the bones of the young Platanista skull in the Museum of the Royal 
College of Surgeons has enabled me to confirm Eschricht’s view; for on removing this 
plate the true palatine is seen, forming as usual the greater part of the anterior and 
* Ossemens Fossiles, 4me édit. (1836) tome viii. p, 130, 
