THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 135 
Formule for various American specimens are as follows: 
BALA{NOPTERA PHYSALUS (L.). AMERICAN. VERTEBRAL FORMULA. 
Museum. Locality. Daten | Ca ey ele. Ca, Total. 
U.S. Nat. Mus., No. 16045 Cape Cod, Mass. 1876? | 7 | 14"| 15 22 (+ 3?)/58 (+ 3?)= 61 
Albany State Mus. n - - 1880 !47 | 14'| 16 25 6 
Ward’s Estab., Rochester | Provincetown, Mass. Tiksieyey NI 7p |) aay || nel te : 
Mus. Comp. Zodl., “ “ 5 ss 
Cambridge, Mass. t Ro RS Ze 63 
Mus. Boston Soc. Nat. 
1880 
Finck Gloucester, Mass. jeteltoy | if \ Ley ss 26 63 
Mus. Acad. Nat. Sci. Phila. | Sinepuxent Bay, Md. | 1868-9 | 7 ee 15 SC a 
U.S. Nat. Mus.* Newfoundland. Igor | 7 | 16 | 14 25 62 
These various formule exhibit a considerable divergence, with no special line 
of separation between the American and European specimens. As already re- 
marked, several of the formule require a certain amount of modification because 
the specimens were somewhat defective, the number of ribs and chevron bones 
actually present probably being less than the original number, These modifica- 
tions will now be considered, and afterwards a revised table of formule. 
RIBS. 
In skeletons of B. physalus which have been examined under favorable condi- 
tions, it has been noted that the last pair of ribs is much shorter than the penultimate 
pair and is not attached to the vertebral column. In other words, the last rib is 
normally a “floating” rib. It has also been observed that the first chevron bone 
is smaller than the second. These facts and other indications lead to the belief 
that museum skeletons in which the last pair of ribs is as long as the preceding 
pair and the first chevron as large, or nearly as large, as the second are defective in 
these parts. Granting this assumption to be correct, we will consider the various 
formule in the preceding tables. 
Regarding the Vlieland Id. skeleton (1851) Flower remarks: “There are 14 
pairs of ribs present; but as the 14th has not the characters usually met with in 
the last rib, and as the 15th vertebra has the end of the transverse process thick- 
ened and showing traces of an articular surface, it is most probable, as Van Beneden 
supposes, that the 15th pair has been lost.” (P. ZS, 1864, p.414). Flower also 
remarks that though Van Beneden cites 14 or 15 as the correct number of lumbar 
vertebree “the place of attachment of the first chevron bone in the skeleton indicates 
but 13 as belonging to this series.” (Jdid., p. 414). The formula for this skeleton 
with these corrections would be: 7, 15, 18, 27 = 62. 
*The 14th pair of ribs is as long as the preceding ones, and hence an additional pair is 
doubtless to be counted. 
* As the first chevron in position is of large size, itis probable that an anterior one is wanting. 
The condition of the inferior carina of vertebra No. 36 indicates that such was the case. 
° The 15th pair of ribs is as long as the preceding pair, and hence 16 pairs may have been 
present originally. * Feetal. 
