18 PROFESSOR FLOWER ON RISSO’S DOLPHIN. 
west coast of France, and the Isle of Wight; and the so-called Delphinus rissoanus three 
times, always at Nice or the Mediterranean coast of France, and, as Fischer has par- 
ticularly pointed out, whenever the date has been recorded, the occurrence has in both 
cases always taken place in the spring or summer (April to July). From this circum- 
stance he concludes that this species (for after a comparison of the osteological and 
other characters he has come to the conclusion that they are one and the same) is migra- 
tory, visiting the shores of Europe in the summer and passing the winter either to the 
south towards the coast of Africa or to the west towards the American continent. 
Although the present examples (occurring in the mouth of the channel so early as 
the end of February) may be thought somewhat to shake this conclusion, it may on the 
other hand prove to be merely a case of an unusually early arrival in our seas. Further 
observations can alone determine the question’. 
Identity of G. griseus and G. rissoanus. 
It has been mentioned that Fischer came to the conclusion that the two species 
(D. griseus and D. rissoanus) ought to be reunited, as had also appeared probable to 
Cuvier*—a conclusion founded on the following considerations :— 
“1°. Que le Dauphin de Risso apparait dans la Méditerranée 4 la méme époque que 
le griseus sur les cOtes océaniques de France. 
“2°. Que sa dentition ne différe pas sensiblement de celle du griseus, puisqu’on peut 
établir la série suivante :— 
= — = (griseus) ; — = (rissoanus). 
“3°. Que le nombre des vertébres, des cétes, des phalanges, en un mot que tous les 
caractcres ostéologiques sont identiques dans les deux espéces. 
“4°, Que les seules différences relevées entre elles portent sur la coloration extérieure 
éminemment variable, et sur la forme plus ou moins ventrue du corps, qui peut tenir a 
Yembonpoint des individus ou a la distension de abdomen par des gaz aprés la mort.” 
Gervais had previously expressed his opinion® that “ Le D. griseus, qu’on appelle 
quelquefois Marsouin de d Orbigny, est trés-peu différent du D. rissoanus; son systeme 
dentaire parait néanmoins devoir l’en faire séparer;” and he gives the following 
diagnostic characters :— 
“Dents supérieures caduques, les inférieures au nombre de cing ou six paires, De/- 
phinus rissoanus. 
‘ It is possible that the Grampus, before mentioned, from the Cape of Good Hope, of which there is a skull 
in the British Museum, named G. richardsonii, may also proye to be of this species; if so, it would indicate 
that the South Atlantic may be its winter habitat. In size it perfectly agrees; but it is rather narrower in 
proportion to its length, and the anteorbital processes of the maxilla are more upturned at their edges, and 
less laterally and anteriorly expanded, and the anteorbital notch is less deep than in the other specimens. 
The teeth are = 
* Ossemens fossiles, edit. 1836, tome viii. 2e partie, p. 98. 
* Zoologie et Paléontologie Francaises, p, 301. 
