154 ME. W. H. FLOWER OX THE SKELETON 



inches. 

 Greatest breadth at postorbital processes of frontals .... 8 - 8 



Breadth of anterior narial apertures 2 - 4 



Breadth of rostrum at base 4 - 7 



Breadth of rostrum at a quarter of its length from base ... 2-9 



Breadth of rostrum at the middle 1-85 



Breadth of rostrum at three-quarters of its length from base . 1*4 



Length of upper tooth-line 11-2 



Mandible. Length of ramus IS - 



Length of symphysis 5 -5 



Length of tooth-line 11- 



Breadth at condyles S - 



Height at coronoid process , . . 3-6 



The occipital foramen is subcircular, slightly higher than broad. The tentorium is 

 largely ossified. The temporal fossa; are bounded by very prominent ridges. The 

 postorbital processes of the frontals do not meet the squamosals by a space of 2 inches. 

 The anteorbital process is well marked, its depressed outer extremity is formed by the 

 jugal. The styliform portion of the jugal is 4 inches long. The median postnarial 

 prominence of the frontal is strongly marked, and rises slightly higher than the supra- 

 occipital or the nasals ; the latter are ankylosed both to the frontals and the ethmoid. 

 The narial apertures exhibit the usual want of symmetry, inclining to the left. The 

 upper extremity of the left prsemaxilla is shorter and much more attenuated than that 

 of the right. The rostrum is rather broad at the base, and gradually tapers towards the 

 middle ; it then becomes much compressed, and retains very nearly the same breadth to 

 its termination. Correspondingly the palate is broad and flat behind, but narrow and 

 with a deep median groove in its anterior two-thirds ; a narrow strip of the vomer 

 appears for a space of 2^ inches in the hinder part of this groove ; as in the allied 

 forms, there are no lateral grooves. 



The palate-bones are of larger extent than in most Dolphins ; and the form of the 

 pterygoids is quite peculiar (see PI. XVIII. fig. \,pt): instead of meeting in the 

 middle line and concealing the hinder edge of the palatines, they are widely separated 

 throughout their whole extent, and gradually recede from each other till their hinder 

 apices are 2 inches apart. In the other large Stenos, as in nearly all other Dolphins, 

 the pterygoids are in contact in the median line for a distance of 2 inches. In Steno 

 lentiginosus, Ow., the inner edges of the pterygoids do not meet, though they are 

 parallel for the greater part of their extent. In I). gadamu, which Owen places in 

 this section, and Gray in the genus Clymenia \ the pterygoids appear to resemble those 

 of the present species ; the skull, however, cannot be confounded with it, as it is much 

 smaller, has a broader and shorter rostrum, and less numerous teeth. 



1 Synopsis, p. 6. 



