Dr. H. Burmeister on two Species q/" Balsenoptera. 415 



the thirty-fifth vertebra in each individual, which vertebra is 

 one of the largest of the skeleton. This vertebra in B. pata- 

 chonica has a height in the body (with the spinous apophysis) 

 of 30 inches, of which 10 are occupied by the body, and a 

 breadth between the transverse apophyses of 34 inches, the 

 breadth of the body being 12 inches ; whereas in B. intermedia 

 the same vertebra is 28 inches in height, with 12 inches in 

 height of the body, and 32 inches in breadth, with 14 inches 

 in breadth of the body ; which difference appears to nie suf- 

 ficient indication of a specific difference between the two 

 animals. 



The fifty-eight and a half vertebrse are distributed in the 

 following manner. There are seven well separated in the 

 neck ; the five posterior very slender, two inches thick in the 

 body, and with two free apophyses excepting in the first two 

 (the atlas and axis), which are a good deal larger and have not 

 free apophyses, the atlas on both sides, the axis on the an- 

 terior side. The axis has two large closed lateral wings, in- 

 cluding an oval aperture ; the three following are open, with 

 two curved apophyses, but separated at the end; the sixth 

 has a lower and shorter apophysis ; and the last has no lower 

 apophysis at all. In B. intermedia all the vertebrje of the 

 neck are broader in the body, but the apophyses are shorter ; 

 and this species has a lower and tolerably large apophysis on 

 the sixth vertebra, which is wanting only on the seventh. 



The seven vertebrte of the neck are followed by sixteen 

 dorsal vertebraj, with the same number of pairs of ribs — that 

 is, one pair more than in the other species, now called B. in- 

 termedia. This difference seems to me of great importance, 

 principally on account of the constant difference of the 

 corresponding ribs, which are all longer and larger to the 

 very end in B. intermedia than in B. patachonica^ and very 

 different also in the shape of the upper part of the rib, and of 

 the tubercle of each rib. Each rib of the first pair is 3| feet 

 in length in B. patachonica and 3f in B. intermedia. In the 

 former species the head of the rib is slender and the tubercle 

 rather large ; in the latter the small tubercle can scarcely be 

 said to be separate, and the head of the rib is larger, scarcely 

 separated from the neck, which is also large. The second rib 

 of B. intermedia is 5 feet in length, and the same rib in B. 

 patachonica 4^ feet; the longest rib, which is the sixth, measures 

 in the former species 7 feet 2 inches, and in the latter 6 feet 

 8 inches. We may infer from these differences that the body 

 of B. intermedia must have a much larger circumference than 

 that of the other species, and that its general shape must be 

 less slender, as we said at the beginning of our comparison. 



