THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 



201 



BALJENOPTERA ACUTO-ROSTRATA LAC. EUROPEAN AND AMERICAN. VERTEBRAL FORMULA. 



The agreement as regards number of dorsal vertebrae shown in the foregoing 

 table is quite remarkable, and is in contrast with the variation found in other 

 species of Balcenoptem, and among the Cetacea generally. It will be seen also that 

 the lumbars show a variation of but one. The variation in number of caudals, ex- 

 clusive of that due to defects, probably does not exceed two. Eschricht remarks 

 as follows regarding the vertebral formula of the Norwegian Vaagehval (36, 322) : 



" In all the foetuses of the Vaagehval examined by me, I found, 48 vertebrae, of 

 which 7 were cervicals, 11 dorsals, 12 lumbars, and 18 caudals; furthermore, this 

 was exactly the number of vertebrae in the whole spine and in each of its different 

 sections, not only in the complete Vaagehval skeleton from Bergen examined by me 

 and the specimen examined in Christiania in 1844 (p. 304) as well as that sent 

 from the west coast of Jylland in 1841 ( Videns. Sets. Skr., 11, p. 175), but also 

 in the three small finback skeletons sent down from Greenland. Likewise, accord- 

 ing to both Governor Christie's written communication regarding those Bergen 

 Vaagehval skeletons which did not come under my observations, and Dr. Kroyer's 

 statements relative to the skeletons of Vaagehvals preserved in the Bergen Museum 

 (Naturh. Tidskr., 2, p. 634), this numerical proportion may be considered constant 

 in the species." 



CHEVRONS. 



The number of chevrons in European specimens is usually nine, but some- 

 times eight. The number in the Massachusetts specimen is nine. 



BALjENOPTERA ACUTO-ROSTRATA LAC. EUROPEAN AND AMERICAN. NUMBER OF CHEVRONS. 



" In all the foetuses of the Vaagchval examined by me, I found 48 vertebrae." ESCHRICHT. 

 9 Should probably add one for penultimate caudal. 



