AKT. 9 A POLLACK WHALE FROM FLORIDA MILLER. 3 



COMPARISON OF THE POLLACK WHALE WITH THE BETTER-KNOWN 

 NORTH AMERICAN FINBACKS. 



Good photographs of the fresh specimen were not obtained at 

 Pablo Beach, and no detailed measurements were taken. Tlie length 

 of the animal is said to have been 45 feet. Nothing can therefore 

 be added to that which was previously known of the external char- 

 acters. From the various published accounts it appears that stranded 

 individuals of the Pollack Whale may be distinguished among the 

 American finbacks by the following peculiarities. 



(1) Size moderate (total length usually ranging from 35 to 50 

 feet), greater than in the Pike ^^'liale (usually less than 30 feet), 

 less than in the Common Finback (usually 55 to 75 feet), and the 

 Blue Wliale (usually 60 to 90 feet). 



(2) Whalebone plates (pi. 20, fig. 2) uniformly blackish horn 

 color, the extremely fine and hair-like bristles a very pale horn color 

 appearing conspicuously whitish by contrast, and therefore usually 

 described as " white " (plates and coarse bristles all pale horn color 

 m the Pike WHiale, all blackish horn color in the Blue Whale, some 

 dark, some light, in the Common Finback). 



(8) Folds on the throat in region between the flippers about 40 

 to 60, as in the Pike "\^n[iale, not about 60 to 80 as in the large Com- 

 mon Finback and Blue '\\niale. 



(4) Flippers uniformly dark colored, as in the Common Finback 

 and Blue Whale, not conspicuously pied as in the Pike lAHiale. 



(5) Dorsal fin relatively high, as in the Pike AVliale (its height 

 equal to about one-third depth of body measured at base of fin; in 

 the Common Finback and Blue "^Vliale it is equal to only about one- 

 fifth or one-sixth the depth of body in same region). 



Tlie structure of the skeleton in the Pollack Whale shows many 

 pecularities as compared with that in the other American finbacks. 



ShtiU (pis. 1-4). — The skull has the general form seen in the Pike 

 "Wliale and the Common Finback — that is, the rostrum when viewed 

 from above or below is triangular in outline, with lateral margins 

 essentially straight or faintly curved from base to tip. It therefore 

 differs conspicuously from the skull of the Blue Whale, in which the 

 rostrum is not triangular, its sides being parallel, or nearly so, from 

 the base almost to the middle, then rather strongly curved to the 

 tip, the curve of each side following approximately the arc of a 

 circle whose radius is about as long as the intermaxillary bone. 

 Further comparison with the Blue A^Hiale is scarcely necessary, as 

 this animal is so different from the other finbacks that I do not re- 

 gard it as a member of the genus BaJmioptcra. It may be men- 

 tioned, however, that in the Pollack \"Sniale the nasals are relatively 

 larger than in the Blue Wliale (their length is contained about 9^ 



