8 



BRITISH FOSSIL CETACEA 



remaining prefrontal cartilage, into which had extended a few spiculse of bone from 

 the lateral premaxillary walls (22', 22') of the deep cavity left between them by reason of 

 the defect or arrest of ossification of this part, as in Ziphius cavirostris (fig. 1). It is 

 most interesting to find indications of a similar structure in the original figure taken from 

 Cuvier's type-specimen of Ziphius cavirostris, in pi. xxxviii, fig. 2, of Prof. Gervais' 

 excellent work above cited.^ 



Fig. 4. 



Ziphius indicus, V. B. ; l-8th nat. size. 



In Ziphius indicus, at the distance of 9 inches from the upper nostrils, ossifica- 



' Dr. Gray supposes this figure to be from a specimen distinct from that figured by Gervais, in his 

 plate xxxix ; be observes, " The skull of this genus (viz. Petrorhynchns) resembles in several particulars 

 the skull of Ziphius cavirostris figured by Gervais (' Zool. et Paleont. fran9.,' t. 39) ; but the cavity on 

 the crown of that species is only slightly developed, though it is apparently rather more developed in the 

 other specimens figured on the plate, t. 38 (figs. 1, 2) of that work, and the vomer is sunk in a groove, as 

 in the other Ziphioid genera" ('Catal. of Whales, &c.,' p. 346). But the figure 1 of pi. xxxviii, Gervais, 



