138 



THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 



the Museum of Comparative Zoology, Cambridge, Mass., the first three pairs of 

 ribs have capitular processes ; in the Gloucester (Mass.) specimen, the 2d and 3d 

 pairs; in No. 16045, U. S. N. M., Cape Cod, Mass., the 2d, 3d, and 4th pairs. 



In the type of B. tectirostris (Cope) the 1st rib is double-headed, as shown in 

 pi. 4, fig. 4, and pi. 6, fig. 3. The rib is 30| in. long (straight) to the middle point 

 of the broad distal end ; the breadth at the distal end, 7 in. The supplementary 

 head is 6 in. long in a straight line, and 2 in. broad at the free end. A pre- 

 cisely similar first rib is described by Van Beneden as occurring in the Borselaer 

 specimen (4, 27-30, fig.). This peculiarity was formerly considered of specific 

 or even generic importance, but recent investigations, especially those of Sir Win. 

 Turner, lead to the conclusion that this conformation is properly to be regarded as 

 an individual variation (see Turner, Journ. Anat. and Phys., 5, 1871, pp. 348-361). 



CHARACTERS OF VERTEBRAE. 



* 



The number of vertebrae in B. physalus has already received attention (p. 134). 

 The characters of the cervical vertebrae given by Flower in the diagnosis cited in a 

 previous page (p. 131) are found in American specimens (see Dwight, 35, 213-217, 

 pi. 1, and this work, pi. 4, fig. 4, and pi. 5, fig. 1, type of E. tectirostris Cope). 

 Struthers (86, 32) gives as characteristic of the 3d to the 7th cervicals of adult 

 . physalus the following : 



3d and 4th. Transverse processes slanting obliquely backward. 



5th. Transverse processes directed horizontally outward. 



6th. Transverse process directed a little forward. Inferior transverse process 

 usually more or less incomplete. 



7th. Supeiior transverse process robust ; inferior transverse process almost 

 entirely absent. 



These characters were found in the Gloucester (Mass.) specimen described by 

 Dwight (35, 213, 217, figs. 5-7), and occur also in No. 16045, U. S. N. M., Cape 

 Cod, Mass. 



Among the characters of the caudal vertebrae which may be considered impor- 

 tant are the positions in which the foramina and processes appear or disappear. 

 Some of these points in European and American specimens are brought together in 

 the following table : 



BALMNOPTERA PHYSALUS (L.). EUROPEAN AND AMERICAN. CHARACTERS OF VERTEBRAE. 



