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PBOr. W. H. FLOWER ON THE GENUS MESOPLODON. 

 Dimensions of the Bones of the Pectoral Limh. 



Summary and Conclusion. 



The evidence which has accumulated up to the present time is sufficient to 

 show that there are at present existing in many parts of the ocean several distinct, 

 though closely allied, species of Cetaceans, united by common characters, to which the 

 generic name Mesoplodon may be applied. The reasons for the choice of this name 

 in preference to many others which have been applied to members of the group have 

 been fully stated in a previous communication ^. 



The nearest known ally to these animals is unquestionably JBerardius, although 

 in some characters, especially the form of the spinous processes of the vertebrae, they 

 rather resemble Ziphius and Hyperoodon. 



With the three genera just named they form a natural group, allied on the one 

 hand to Physeter, and on the other to the true Dolphins; but their affinities are, 

 on the whole, nearest the former, which, indeed, may be regarded as a highly special- 

 ized form of the same type, Hyperoodon coming next to it, and Mesoplodon being the 

 most generalized. 



Gervais, who founded the name Mesoplodon, making M. hidens or sowerhiensis the 

 type, did not include two species assigned to it above, viz. M. densirostris and 

 M. europmus, but put them in another genus, Bioplodon, an arrangement to which he 

 adheres in his recently published ' Osteographie des Cetaces.' He has, however, never 

 clearly defined the distinction between the two groups ; and it is exceedingly difficult 

 to discover any characters common to the two last-named species which is not also pos- 

 sessed by the former. This has been the opinion of most authors who have investigated 

 the subject subsequently, as Duvernoy, Fischer, E. Deslongchamps (who, however, 

 uses the name Bioplodon for the whole genus), and Van Beneden. A close 

 examination of the cranial characters of the known species does, however, reveal 



' As these measurements were taken after drying, the disproportionate shortness of the manus of the second 

 specimen may in a great measure be accounted for by the shrinking of the cartilages, which occupy in it a far 

 more considerable proportion than in the older animal. 



' Trans. Zool. Soc. vol. viii. p. 208. 



