254 LILLJEBORG ON THE 



this to be 3" shorter than in Companyo's rorqual.^ As the difference of length of the dorsal 

 vertebrae probably extends, as usual, to the length of the other vertebræ, we may thus partially explain 

 the difference of length of body between this rorqual and those obtained in Norway, but this differ- 

 ence in length of body is rather too great to be satisfactorily explained in this manner. That it, 

 notwithstanding it had the dorsal vertebræ considerably longer than those on the skeleton in Bergen, 

 had them no wider than on this (width 0-34 met., or 1' 2"), seems to be in consequence of its being 

 younger, while the latter skeleton was from an old whale. This will be seen in comparing the dimen- 

 sions of the first lumbo-sacral vertebra, according to the table below, of the skeleton in Copenhagen, 

 which was from a young whale, with those of the same vertebra on the skeleton in Bergen. Although 

 this vertebra in the latter skeleton is only |" longer than in the former, it is somewhat more 

 than 3" wider. We find, also, no difference of consequence in the form of the vertebræ in 

 Companyo's rorqual and ours, although those of the former are of much larger size. Of the devia- 

 tions mentioned here, to which may be added that Companyo's rorqual, to judge from the figures and 

 measurements, had the ulna somewhat narrower, those based upon the form of the atlas and axis 

 are undoubtedly the most important, and might possibly denote specific differences ; but as the figures 

 given by Cornpanyo do not seem to be executed with particular accuracy, and these vertebræ are subject 

 to some changes, both from age and from individuality, it has not been considered justifiable to arrange 

 them as distinct species, when they agree in so many other respects ; more accurate and positive 

 comparison would be necessary for this. The difference existing in the relation between the anterior 

 extremities and dimensions of the body are not worth attention, considering the great variations exist- 

 ing in this respect, according to what Eschricht has shown. The earlier authors, Linné and others, 

 have described their Balæna musculus too incompletely to be mentioned in the synonymy; such is also 

 the case with Lacépéde. It may be possible that Balænoptera jubartes and B. rorqual, in Lacépéde 

 (' Hist, nat, des Cét.), belong to this species (such is the opinion of Gervais), but the descriptions of 

 them are so indefinite, that even other Balænopteræ might be included in the same. Gervais has even 

 considered Lacepede's Balænoptera acuto-rostrata as a synonym,^ although the description, as well as 

 the figures of it, evidently show that it belongs to another species, viz., Fabricius's Balæna rostrata. 

 As for Cuvier, he has not given any more minute description of this rorqual, but the figure of the 

 skull furnished by him agrees so well with this, that there is no doubt that this is the species that he 

 calls " Rorqual de la Méditerranée." Schlegel has in his ' Abhandlungen,' &c., united all the 

 Balænopteræ into one species, which in the first volume he calls Balæna sulcata Arctica, and in the 

 second volume Balænoptera Arctica. The specimen — a young male somewhat over 40' in length — 

 that is particularly described by him in the second volume under the latter name, seems to belong to 

 this species, and is therefore here mentioned as a synonym, partly on Eschi'icht's authority, and partly 

 because Eschricht, from personal examination of its skeleton, has been enabled to add one vertebra to 

 those stated by Schlegel, whereby their number seems fully to correspond with those of the Razorback. 

 It seems, however, to have presented some deviation in colour, and had only 15 processus spinosi 

 inferiores, while the specimen examined by me had 18 such processes. The skeleton described by 

 Van Beneden had 17. 



' [Since this was written, I have been informed by Dr. Koren that the length of the corpus of 

 the last dorsal vertebra of the Bergen rorqual is 9". — 1865.] 

 ^ 'Zoologie et Paleontologie Fran9aises.' 



