PROFESSOR FLOWER ON RISSO’S DOLPHIN. 9 
in the comparative narrowness of the rostrum. The general aspect of the upper surface 
somewhat recalls that of a Beluga. 
There are no traces of alveoli in the maxilla; but there is a slight depression in the 
usual situation of the upper teeth, with numerous openings of vascular canals. At the 
extreme tip of each premaxilla is a conspicuous rounded foramen of the same nature!. 
The petrotympanic bones closely resemble those of Glodicephalus, and are almost of 
the same size as those of an animal of that genus of nearly double the length of the 
present specimen. 
Fig. 3. 
Fig. 3. Periotic and tympanic bones united, outer surface. Fig. 4. Periotic and tympanic bones united, under 
surface. Fig. 5. Periotic bone, under surface. Fig. 6. Tympanic bone, upper surface. All the 
natural size. 
per, periotic ; ty, tympanic; , posterior end of the periotic, answering to the mastoid of ordinary mammals; a, principal 
articular surface between periotic and tympanic; ¢, fissure for Eustachian canal at anterior extremity of tympanic; ¢.a.m, 
external auditory meatus ; ¢.p./, external posterior lobe of tympanic; 7.p./, internal posterior lobe of tympanic; g, groove 
between these lobes ; 7, fenestra rotunda in periotic; a.f, aqueduct of Fallopius; s, stapes. 
The thyro-hyals are ankylosed to the basi-hyal, but with distinct marks remaining 
of the original suture. The thyro-hyals are more flattened and less tapering at their 
free extremities than in Globicephalus; and the basi-hyal has not the same median 
prolongation in front for the attachment of the anterior cornua. 
The principal dimensions of the skull are as follows (the measurements of the 
1 This is eyidently the foramen thus described by Fischer, “En avant des intermaxillaires on voit deux 
petits trous ot devaient étre enchassées les incisives rudimentaires.” He appears also to have taken the other 
vascular foramina in both upper and lower jaws for alveoli of rudimentary teeth (Joc. cit. p. 367). 
VoL. vill.—ParT I. March, 1872. c 
