1883.] PROF. FLOWER ON THE DELPHINIDiE. 473 



wide open space behind. Between these forms are several inter- 

 mediate conditions. 



Alter the separation of the genera named on p. 468, it is possible 

 to discriminate among the remainder at least seven distinct types, 

 apparently worthy of generic designation, the characters of wbich 

 will now be considered. 



Cephalorhynchus. 



Cephalorhynchus, Gray, Cat. Cetacea Brit. Mus. p. 106 (1850). 



This name may be applied to a group of small-sized Dolphins, 

 which appear to be characterized externally by an obtusely triangular 

 (not falcate) or rounded dorsal fin, small, ovate, or oblong pectoral 

 fins, and rather short rounded snout without groove separating a 

 distinct beak. Both externally and in some of their osteological 

 characters they resemble the members of the genus Phoccena. 



In the skull the rostrum scarcely exceeds half the entire length, 

 is broad at the base, and gradually tapering, with convex lateral 



Fig. 4. Palate of dijltalorht/iwhus heiwisidii^. 



borders. The palate is smooth, that is, without the deep, lateral, 

 longitudinal grooves characteristic of the genus Delphiuus as now 

 restricted. The pterygoid bones are short and separated from one 

 another by a considerable interval. The outer edges of the pre- 

 maxillse form a prominent elevated ridge on each side of the anterior 

 end of the narial aperture. The upper surface of the rostrum itself 

 is very smooth, and evenly rounded from side to side, the surface of 

 the premaxillae in this region being flat and not distinctly elevated 

 above the maxillae. The teeth are small (less than 3 millims. in 

 diameter^), 25 to 30 in number in each side of each jaw. Vertebrae : 

 C. 7, D. 13, L. 15, C. 30 or 31 ; total 65 or 66. 



The type and best known species of this group is that described 

 by Gray (from a stuffed specimen formerly in the Museum of the 

 College of Surgeons, now in the British Museum), in the ' Spicilegia 

 Zoologica ' (p. 2, 1828) under the name of Delphinus heavisidii. It 



' This figure is from the '■ Osteographie des Cetaces" of Van Beneden and 

 Gervais, pi. xxvi. fig. 1 a. All the others are from specimens in the Museum 

 of the Koyal College of Surgeons. 



^ This measurement is in the antero-posterior direction, at the base of the 

 crowns of the largest teeth in the middle of the series. 



