PKOFESSOE FLOWER ON RISSO'S DOLPHIN. 21 



Skull. Rostrum and cranium proper of nearly equal length. Upper surface of rostrum 

 very broad and flat', rounded in fi'ont. The prsemaxillse at the middle of the rostrum 

 as wide as, or wider than, at the base, and very nearly or completely concealing the 

 maxillae in the anterior half of the rostrum. Upper surface of the prsemaxillse in front 

 of the narial apertures strongly concave. Upper surface of the skull behind the narial 

 apertures raised into a strong prominence, of which the nasal bones form the apex. 



Mamcs veiy long and pointed, the number of phalanges (including the metacarpals) 

 in the different digits being respectively I. 3-4, II. 13-14, 111. 10, IV. 3, V. 1. 



Grampus. — Teeth, none in the upper jaw. In the mandible 3 to 7 on each side, 

 confined to the anterior part of the ramus close to the symphysis. 



Vertebrw. C. 7, D. 12, L. 19, C. 30, total 68. 



Skull. Rostrum slightly shorter than cranium proper, its upper surface moderately 

 broad and flat, slightly expanding laterally in front of the notch, then tapering gradually 

 to the apex. The praemaxillae not so wide at the middle of the rostrum as at the base. 

 Upper siu-face of the pi-semaxillse in front of the narial apertures convex. Upper 

 surface of the skull behind the nasal apertures rounded. 



Manus long and pointed, the number of phalanges (including metacai-pals) in the 

 different digits being I. 2, II. 10, III. 8, IV. 3, V. 1. 



DESCRIPTION OF THE PLATES. 



PLATE I. 



Fig. 1. Adult female Risso's Dolphin, caught neai' the Eddystone Lighthouse, February 



28th, 1870. 

 Fig. 2. Upper surface of the head of the same. 

 Fig. 3. Upper view of the tail of the same. 



From drawings by Mr. R. W. Sherwin. 

 Fig. 4. Very young female Risso's Dolphin, bought in Billingsgate Market, March 30th, 

 1870. 



From a drawing by Mr. E. Gerrard, jun. 

 All 1*5 the natural size. 



PLATE II. 



Fig. 1. Side view of the skeleton of the adult Risso's Dolphin. 

 Fig. 2. Upper view of the same skeleton. 

 Fig. 3. The sternum of the same, from below. 

 Fig. 4. Skull of the young animal. 

 All g^ the natural size. 



' In the skuDs of very young animals these special characteristics of the fjenus are but slightly developed, the 

 rostrum being much more narrow in proportion to its length than in adults. 



VOL. VIII. — PART I. March, 1872. e 



