38 PKOFESSOB OWEN ON INDIAN CETACEA. 



The maxillary (PI. XII. fig. 1, PI. XIII. figs. 1 and 2, 21) forms the major part of the 

 bony roof of the mouth : a small triangular strip of the premaxiUary (PI. XIII. fig. 2, 22) 

 is wedged into the short anterior interspace between the maxillary (x) and vomer (i3'). 

 The palatal surface (2i») is moderately convex transversely, straight lengthwise, and 

 is impressed by an alveolar groove (al) retaining one socket and tooth (PI. XII. 

 fig. 1, ^) at the fore end and continued in a straight line backward for 3 inches 

 (rather more on the left, rather less on the right side) without indications of 

 alveoli, and m a line not parallel with the outer margin of the bone, but receding 

 to a distance of 1 inch from it, posteriorly ; so that the teeth, if developed there, would 

 be rather palatal than marginal in position. The outer border of the maxillary thickens 

 near the malo-maxillary fissiu-e (21, /■), with a smooth convex exterior. That fissure dilates, 

 as it sinks obliquely backward and inward, to a breadth of from 3 lines to 4 lines, its 

 depth being 1 inch 6 lines (/c). These fissures mark ofif the rostral portion of the skuU, 

 which is here an equilateral triangle, including above (PI. XIII. fig. 1) parts of the 

 vomer (i3), prefrontal (i-i), prcmaxillaries (22), and maxillaries (21) : the surface so formed 

 is concave transversely at its posterior three-fourths, almost straight longitudinally. The 

 maxillary, expandmg backward beyond the rostrum, bends (at k, fig. 1) round the upper 

 and back part of the malo-maxillary fissure ; and in close conjunction (here partial con- 

 fluence) with the malar (26), it forms the large smooth tuberosity (21,26) external to 

 the fissure: from the tuberosity the convex raised border of the posterior expanded 

 plate of the maxillary comes into connexion with the frontal (11), whence it subsides 

 to form a deep hoUow as it sweeps inward to rise again upon the bifurcate sinuous ridge 

 (ib. 15, 15") which divides this singular postnarial tract, or spermacetic cavity, of the upper 

 surface of the cranium. The total breadth of this cavity is 6 inches 4 lines, the posterior 

 three-foui-ths of its crrcumference, so bounded by the maxillaries and describing as much 

 of a cu-cle, being a little produced backward, subangulaiiy, at the hindmost part : the 

 open anterior foui-th is continued upon the more shallow concavity of the triangular 

 rostrum. The right maxillary is vertically pierced by two foramina (PI. XIII. fig. 1, a, h), 

 which converge to the common inferior outlet (ib. fig. 2, d). The upper fissure between 

 the maxillary and premaxiUary widens and deepens as it extends backward, and terminates 

 in the canal (fig. 1, c), also conducting to the fossa (fig. 2, d), which, as it transmits 

 maxillary branches of the fifth pan- from the orbit to the exterior of the skull, is 

 homologous with the antorbital foramen of other mammals : the altered position of the 

 outlet, as regards the orbit itself, is the result of the reflection, so to speak, of the facial 

 surface and nasal plates of the maxillaries upon the forehead above and behind the 

 orbits. 



The pteiygoids (PI. XIII. fig. 2, 24) meet at the midsurface of the roof of the mouth, 

 and extend the palatine suture {iij) backward beyond the palatine bones (20). From this 

 line each pterygoid extends outward and backward, and divides into an internal and 

 external pterygoid plate : the former terminates m a short triedial process, representin<^ 



