502 PROF. FLOWER ON THE DELPHINID^. [NoV. 20, 



those in the skeleton and dentition, numbers of nominal species, 

 founded on slight differences of external or cranial characters, which 

 now encumber our lists, must fall to the ground. But valuable as 

 these observations are they admit of much further extension ; in- 

 deed, as Fischer truly says, "nous ne sommes qu'au debut de 

 r^tude des variations chez les Dauphins." 



The observations on the osteological and dental characters maybe 

 thus summarized : — The average length of the full-grown animal is 

 rather more than 2 metres (6 feet 7 inches), the longest measurmg 

 2-150 metres. The males and females, when adult, do not differ in 

 size. The differences of the skulls of the two sexes has already been 

 indicated (p. 470). The longest skull of which the dimensions are 

 given (a female) has an extreme length of 460 millim. 



The number of the teeth varies considerably in each jaw and each 

 side. Sometimes there are more in the upper than in the lower jaw, 

 and sometimes the reverse is the case. The average number for each 

 side of each jaw of ten individuals was 47, the highest number ob- 

 served being 53 and the lowest 39. 



The number of vertebrae ranges between 73 and 75, 74 being the 

 most usual. The two first cervical vertebrre are\uiited, the remainder 

 free. The ribs are either 14 or 15 pairs, these numbers occurring 

 apparently with about equal frequency. In one case Ifi were ob- 

 served. In two cases the numbers differed on the two sides of the 

 same individual, there being 14 ribs on one side and 15 on the 

 other. 



In the manus there was some variability in the number of elements 

 composing each digit ; but this may have arisen partly from the dif- 

 ficulty of preserving and covmting them. The numbers given are: 

 —I. 2 to 3, II. 8 to 9, III. 5 to 7, IV. 2 to 4, V. 1 to 2. 



After the examination of these Arcachon specimens and of others 

 from the British Channel and the Mediterranean, Fischer arrived at 

 this important conclusion : — " Je pense que le Dauphin vulgaire, qui 

 semble habiter presque toutes les mers du globe, presente d'innom- 

 brable races ou varietes. Chaque bande de ces Cetaces constitue 

 en quelque sorte une famille, et les individus ayant une meme prove- 

 nance ont des caracteres communs qui se perpetuent par la voie d'he- 

 redite. Les caracteres distinctifs de ces bandes ou families sont 

 fournis par la coloration du corps, beaucoup plus variable chez les 

 Dauphins qu'on ne I'admet generalement, par le plus ou moins de 

 largeur du rostre, et par le nombre des dents." 



Let us now examine into the evidence of the almost cosmopolitan 

 nature of this form. All considerable osteological collections aboiuid 

 in skulls undistinguishable from the ordinary Delphinus delphis ; 

 but as very few have any localities assigned to them or any indica- 

 tion of their external or remaining osteological characters, they are 

 of little value for the purpose, except as showing that it is a very 

 abundant and probably wide-spread form. We have, however, a 

 tolerably complete knowledge of a Delphinus very frequent in the 

 seas around Australia and New Zealand, D. novcB-zealandicB of Quoy 

 and Gaimard (' Voyage de I'Astrolabe,' p. 49, t. 28), and D.forsteri, 



