AKT. 9 A POLLACK WHALE FROM FLORIDA MILLER. 7 



slight development of the collum in this specimen and in the Pol- 

 lack "Wliale from Florida may in each case be an individual peculi- 

 arity ; that immaturity does not account for it is shown by the fact 

 that both skeletons came from aged individuals with the epiphyses 

 of the vertebrse so completely fused that they are scarcely distinguish- 

 able. The separated ribs of the Common Finback shown by True 

 (pi. 6, fig. 1) are from an animal too young to have developed the 

 charactei*s in question ; the same is the case with those of the Pollack 

 Whale figured by Andrews. In the mounted skeleton of a Common 

 Finback from California, photographs of which are reproduced by 

 True as text figures 95 and figure 4 of j)late 6, tlie long collum of 

 ribs 2, 3, and 4 may, however, be distinctly seen, especially in figure 95. 



Chevron hones. — The chevron bones were all lost before the skele- 

 ton was received in Washington. 



Sternum (pi. 18, fig. 1). — The outline of the sternum differs from 

 that in all of the 25 sterna of the Common Finback figured by True 

 on pages 140 and 141 and of the 10 of the Pike Wliale on page 205. 

 The portion of the cross which lies in front of the transverse arms 

 is relatively larger than in any of those of the two better-known 

 species ; the length of the posterior median projection, in proportion 

 to the width of the sternum, is about the same as the average for 

 the Common Finback, but is less than in any of the sterna of the 

 Pike Whale. 



Scapula (pi. 17). — As compared with the scapula of the other 

 American finbacks, so far as can be judged from very inadequate 

 material, that of the Pollack Whale is distinguishable by greater 

 width in proportion to the height and by ^ the length, distinctness, 

 and narrowness of the neck. The least width of the neck above the 

 base of the coracoid process is contained a little more than four times 

 in the greatest width of the blade, while in the other Atlantic fin- 

 backs it appears to be usually contained about three and one-half 

 times. The acromion process is long and slender, with parallel sides, 

 as in the Pike Whale, and without the tendency to broaden toward 

 the tip, which is seen in the acromion of the Common Finback and 

 the Blue Whale. The coracoid process is more slender than appears 

 to be usually the case with that of the two largei- finbacks; it thus 

 agrees with the coracoid of the Pike ^^Hiale. 



Bones of the arm and hand (pi. 19). — The bones of the arm are 

 characterized by length and slenderness, features which are partic- 

 ularly noticeable in the humerus and radius. Apart from this gen- 

 eral feature, which appears to distinguish the arm from that of 

 all the other finbacks, I do not detect any peculiarities worthy of 

 special note. 



The metacarpals and such phalanges as are preserved agree in 

 general form with those of the Common Finback and tlie Pike 



