b PROCEEDINGS OF THE NATIONAL MUSEUM. vol.66 



by Meiige,' they are even shorter, little more than one and one-half 

 times the depth of the centra. In the Pike Wliale, however (see 

 True, pi. 27, fig. 2), the relative height of the spinous processes is 

 essentially as in the Pollack Whale. With regard to the backward 

 slant of the spinous processes the Pollack Whale differs from both the 

 Common Finback and the Pike Whale. In the two better-known 

 animals the processes rake backward to such a degree that in the 

 median portion of the series the entire upper margin of the process 

 is frequently carried back beyond the level of the posterior margin 

 of the centrum. (See figures by True and Menge already referred 

 to. This character is readily observed in a mounted skeleton of 

 the Common Finback from Cape Cod, U.S.N.M. No. 1G045. It is 

 even more j^ronounced in a skeleton of the Blue Whale from New- 

 foundland, No, 49757.) The spinous processes in both the Florida 

 skeleton and the Japanese specimen (Andrews, fig-s. 18-20) are, on 

 the other hand, so little inclined backward that in no vertebra of 

 either individual does the antero-upper angle of the process attain 

 the level of the posterior articular surface of the centrum. A near 

 approach to this condition may be seen in some of the Japanese 

 vertebrae, notably lumbars 3 and 8, but all the vertebrae in this in- 

 dividual appear to lack the epiphyses, thus making the backward 

 extension of the centra less than normal. The more detailed features 

 of the vertebrae are shown by the photograplis reproduced in the 

 plates 



Ribs (pi. 16J. — The bifid head of the first rib, a character nearly 

 always present in the Pollack Whale, is clearly shown by the Florida 

 specimen. In another peculiarity the ribs differ from those of the 

 mounted skeletons of the Common Finback (No. 16045) and Blue 

 Whale (No. 49757) in the National Museum: The combined neck 

 and head form a large and conspicuous process in the second, third, 

 and fourth ribs of the two better-known finbacks, projecting inward 

 toward the centra beyond the tubercle; this projection is a mere ir- 

 regular knob on the second and fourth ^ rib of the Pollack Whale, 

 fairly w^ell developed, though short, on the third only. This is prob- 

 ably a specific character, as the devolpment of the combined neck and 

 head is essentially alike in both of the skeletons of the better known 

 species, though the Blue Whale is fully adult, while the Common 

 Finback is an immature individual with the epiphyses of the vertebrae 

 not fused to the centra. In the skeleton of the Pike ^Wliale (No. 

 20931), however, a third condition is represented: The collum is 

 present and distinct but short on the second rib, very rudimentary 

 on the third, and absent from the fourth. It is possible that the 



^ Schr. natui-forsch. Gesellsch. Danzig, vol. 3, pt. 4. 1875. 



* Too large as restored, judging by the structure of the left rib. 



