434 PROF. W. H. FLOWER ON THE GENUS MESOPLODON. 
Dimensions of the Bones of the Pectoral Limb. 




M. australis. M. grayi. 
Scapula: height from middle of external margin of glenoid fossa in. millim, in. millim. 
tovmiddlevof superioripordersla-act. weelae ceeees eee ye eee 8°2= 208 73=185 
Length from anterior to posterior superior angle ............ 12-8=325 11:3 = 287 
Length of pectoral limb from head of humerus to end of second digit 19:0=483 17:0=482 
‘Humerustaléngtih ese... + Sees Coe een os ene see ene §:3=135 5:2=132 
Breadthyatlowor-endie os: ¢ fyeetiic ou aaceee eee bake 2:5= 64 
Radios slonpile ceca crass time cr RL reece ame ce cite 6-0=153 5:6=143 
Ulna: lengthy includmeolecranon),)5.-\- 2 shorts seule Sel 65=166 5-9=150 
Breadth of radius and ulna at lower end ...............-..-- 3:1= 78 30= 75 
Lenpth of amanus!: sheet ct ester ce tem tne te ete ee Te 9:0=229 7-0=178! 





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 Berardius, although 
in some characters, especially the form of the spinous processes of the vertebra, 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. bidens or sowerbiensis the 
type, did not include two species assigned to it above, viz. M. densirostris and 
M. europeus, but put them in another genus, Dioplodon, an arrangement to which he 
adheres in his recently published ‘ Ostéographie des Cétacés.’ 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 Dioplodon for the whole genus), and Van Beneden. A close 
examination of the cranial characters of the known species does, however, reveal 
1 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. 
