18 PEOFESSOR FLOWEE ON EISSO'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 sbores 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 1 . 



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 2 — a conclusion founded on the following considerations : — 



" 1°. Que le Dauphin de Risso apparait dans la Mediterranee a la meme epoque que 

 le griseus sur les cotes oceaniques de France. 



" 2°. Que sa dentition ne differe pas sensiblement de celle du griseus, puisqu'on peut 

 etablir la serie suivante : — 



83 n £S (griseus); £J g (Hssoanus). 



" 3°. Que le nombre des vertebres, des cotes, des phalanges, en un mot que tous les 

 caracteres osteologiques sont identiques dans les deux especes. 



" 4°. Que les seules differences relevees entre elles portent sur la coloration exterieure 

 eminemment variable, et sur la forme plus ou moins ventrue du corps, qui peut tenir a 

 l'embonpoint des individus ou a la distension de l'abdomen par des gaz apres la mort." 



Gervais had previously expressed his opinion 3 that " Le D. griseus, qu'on appelle 

 quelquefois Marsouin de d'Orbigny, est tres-peu different du I), rissoanus; son systeme 

 dentaire parait neanmoins devoir Ten faire separer;" and he gives the following 

 diagnostic characters : — 



" Dents superieures caduques, les inferieures au nombre de cinq ou six paires, Del- 

 phinus rissoanus. 



1 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 prove 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 |=j. 



2 Ossemens fossiles, edit. 1836, tome viii. 2 me partie. p. 98. 



3 Zoologie et Paleontologie Frangaises, p. 301. 



