20 BRITISH FOSSIL CETACEA 



Species — Ziphius angulatus. 



ZiPHius ANGULATUS, Oweu. Plate IV, figs. 1 and 2. 



In this well-marked species the prefrontal mid-tract rises in an angular roof-like 

 manner, the sides of the upper surface of the rostrum so formed sloping from a median 

 ridge at the angle shown in cut, fig. 9, and in the section below fig. 1 in PI. IV. In this 

 specimen the maxillo-premaxillary suture (« in fig. 1) is traceable at the expanded basal part of 



the rostrum, showing the proximity thereto of the (antor- 

 bital) nervo-vascular canal (b) in the beginning of the 

 expanded part of the maxillary bone. The premaxillary 

 foramen {d) is midway between that suture and the 

 prefronto-preraaxillary sutm-e ; this foramen is smaller 

 than in the two preceding fossil species, and in the 

 same degree approaches to the character afibrded by 

 the foramina (rf, PI. I, fig. 2) in the recent Ziphius 

 Layardi. The septum narium (14) rapidly expands, 

 anterior to the nostrils, to the breadth of the mid-tract 

 shown in fig. 1, at two inches in advance of the nostrils. 

 From this part the mid-tract advances, maintaining the 

 same breadth to the middle of the rostrum, and thence 

 gradually contracts, with subsidence of the roof, to the 

 broken anterior end. The right premaxillary shows a 

 superficial groove {v, v) about four inches long, near 

 Section of rostrum, margin of the Hiid-tract, due to a branch of 



the main canal (rf). The corresponding canal, exposed by the fractm-e at in the left 

 premaxillary, ran deeper, and its superficial branch emerged later or further forward 

 upon the surface. The ectomaxillary ridge of the snout (fig. 2, e), commencing at the 

 outer and lower wall of the canal (J), extends forward, gradually subsiding, but not to 

 efi'acement, in the presented extent of the present rostrum, at least on the right side ; on 

 the left side it is interrupted at its middle part by the emergence of a branch canal 

 from h, forming an open narrow groove for two or three inches, beyond which the ridge, 

 though lower, is resumed. 



The sides of the pterygo-palatine keel-like ridge (fig. 2, 24) is almost flat ; anterior to this 

 the lower and lateral parts of the snout show two successive slight swellings, as at y and z. 



