12 



BRITISH FOSSIL CETACEA 



bending outward from the line of their mid-palatal suture, which is G inches in longi- 

 tudinal extent. The free lower borders of the pterygoids approximate and thicken as 

 they pass backward, diminishing but not obliterating their interval, at the hind end of 

 which the thick border of the pterygoid bends abruptly outward for about three inches, 

 terminating in a sharp angle answering to a hamular process. The expanded fore part 

 of the malar (figs. 5 and 7, 2G) shows the beginning of the styliform backward 



continuation. The squamosal (ib., 27) has a 

 prominent, flat, oval facet at the fore part of 

 the ' glenoid cavity,' the concave articular sur- 

 face of which is defined at the back part. Other 

 anatomical particulars not specially concerning 

 the subject of the present ]\Ionograph I here 

 omit. 



An upper view of the mandible is given in 

 cut, fig. 8. The sex of the individual affording 

 the above-described skull is not known. From 

 the size of the alveoli indicating that the ter- 

 minal pair of mandibular tooth-germs were 

 developed, it was probably a female. In Prof. 

 Van Beneden's specimen the developed teeth 

 were but 2^ inches (0 00 5 mm.) in length, 

 and consisted chiefly of root, thickly coated with 

 cement. 



From the correspondence of structure of the 

 upper jaw of the present Cetacean with that in 

 the specimens affording to Cuvier the characters 

 of his genus Zipldus, I refer it thereto ; the de- 

 Mandible of Ziphius indicus. l-8th nat. size, gree of ossification of the prefrontal or cranio- 

 facial cartilaginous constituent of the rostrum, 

 with the proportions of the rostrum, I interpret as specific, and adopt the nomen triviale 

 by which this existing species of Zijjhius has been designated by Prof. Van Beneden 

 (loo. cit.). 



ZiPHius Layardi (DoLiCHODON, Gray). Plate I. 



Having shown, in Ziphius indicus, a partial ossification of the cartilage continued 

 along the groove of the vomer from the septum narium, or coalesced prefrontals, as in 

 Z. cavirostris, Cuvier, I now proceed to demonstrate, in another existing species, the 



