272 LILLJEBORG ON THE 



Pterobalæna minor, varietas Bergensis, Idem. Undersogelser over Hvaldyrene, 



6'° Afhandling, K. Danske Vidensk. 

 Selsk. Skr., 5'^ R., 1 Bd., p. 109.^ 



RoRQUALTis — Knox. Jardine's Naturalists' Library, vol. xxvi, p. 143, pi. 7. 



Note. — H. Rasch has, in ' Nyt Magazin f. Naturvidensk,' 1845, suggested the name of Balæ- 

 noptei'a Eschrichtii for this species. 



Note. — Eschricht mentions several peculiarities in which the Bay whale, that appears on the 

 coasts of Norway, differs from the Greenland, or the genuine B. rostrata, Fabr. The latter has 

 the lateral processes of the 5th and 6th cervical vertebrae forming rings, which is not the case with the 

 former ; it has also the dorsal fin somewhat further back. Eschricht does not consider these differences 

 suflScieiit to be specific, but considei's both forms as varieties of the same species, Pterobalæna minor, 

 variet. Groenlandica and Bergensis. As I have not had an opportunity of making a comparison 

 between these forms, I will follow the authority of Eschricht, although the deviations stated, if 

 constant, might denote specific difference. Although the name given by Fabricius was founded upon 

 an error, as he considered it the same species as Pontoppidan's Balæna rostrata, which, as already 

 shown, is Hyperoodon rostratus, I have considered it right to retain Fabricius' specific name, as being 

 the oldest that with certainty can be applied to this species. 



This is the smallest of all our Balænopteræ. The length of the fuH-grown animal scarcely 

 seems to exceed 32' or 33'. The old male may grow somewhat larger. In comparing the rela- 

 tion of the length of the ribs with the length of the skeleton in this and the preceding species, 

 according to measurements here given, we find that the present species is not of so slender and 

 elongated form of body as the last.^ A similar comparison between the skull and the skeleton 

 shows that it also has a larger head than the other. A young specimen, 15' 10" long, caught at 

 Cherbourg, was, according to Lacépéde, 10' 2" in circumference at the thickest part. A foetus, 

 about 3' long, was, according to Eschricht, 1' 6|" in circumference at the thickest part. Eschricht 

 considers that the form of body of this young specimen could not with certainty be ascertained, 

 in consequence of its loose consistence. Although an older animal, probably, is thicker than a 

 foetus of only ^ the size that it will have when it is brought forth, it is likely that the thickness 

 stated by Lacépéde is too large, and was caused by the animal being distended by gas. The 

 body is rather robust, with its greatest thickness about the middle, according to the figure of 

 the foetus given by Eschricht. It tapers but slightly forward to just above the ejesj from 

 thence it is sharply pointed in front, so that the head is sharply pointed when seen either from 

 above or from the side, with the upper and lower outlines converging about equally. The head 

 is a little sharper when seen from the side than seen from above. The forehead on this foetus 

 seemed somewhat prominent and convex above the eyes. The older animal is, according to 

 Knox's figure, without this convexity. The lower jaw projects distinctly farther than the upper 



^ The variety that occurs at Greenland is there called Tikagulik. Chamisso mentions a small 

 whale, from the sea at Kamtschatka, which is there called Tschikagluch [' Nova Acta, Acad. Cæsar. 

 Leop., t. xii, pars 1, p. 259), and this is considered by Eschricht to be the same as the Tikagulik of 

 the Greenlanders. 



" I have, unfortunately, not had access to any complete description of the external form of the 

 full-arrown animal. 



