248 



ALLEN: NEW ENGLAND WHALEBONE WHALES. 



posteriormost of which are close together, the three or four succeeding ones more widely spaced. 

 The two hindermost bristles are much nearer the edge of the lip than the others, so that the 

 row curves downward here, toward the corner of the mouth. Directly above these two bristles, 

 and standing between the inner and the outer row is a single bristle (see diagram, text-fig. 11). 

 On the upper surface of the snout there are thus eighteen hairs on each side. 



On the lower jaw there are again two rows of hairs on each side, but very differently placed. 

 At the tip of the jaw are two vertical rows of nine bristles each, very close together in the foetus, 

 but three inches apart in an adult and extending the height of the lip. The rows diverge 

 somewhat dorsally but are parallel for the lower three-fifths. The second row is on the side 

 of the lip, and consists of seven hairs, somewhat regularly spaced. The first hair of this row 

 is back from the tip of the jaw at about the beginning of the second quarter of its length. In- 

 stead of running parallel to the convex upper margin of the lip, this row of hairs forms a chord 

 of the arc, on the line with the rami of the jaws. 



The Blue Whale has thus in all 68 of these large hairs, each of which comes from a promi- 

 nent raised follicle. They correspond more or less in position to the vibrissae or 'whiskers' 

 of other mammals, and probably have a tactile function. In adult whales these hairs are 

 sometimes absent, or at all events not easy to find. Possibly they become worn down or may 

 fall out with age. 



It will be seen that the arrangement of the hairs is similar to that in the Finback, but 

 the Blue Whale has a slightly greater number. 



In addition to these prominent vibrissal hairs, there are a number of small hairs at the point 

 of the lower jaw, yellowish in color, and in a specimen I examined at Newfoundland, about 

 fifty in number. 



Baleen. The whalebone plates are larger and coarser than in any of the other Balaenop- 

 terae. The longest measure from 23 to 32 inches in animals of about seventy feet or over 

 (True), but the latter dimension is unusual. The bristles that fray out from the inner margin 

 of the plates are very coarse and stiff, and like the blade itself are wholly coal black. The 

 combination of black baleen including the bristles is characteristic of this species of Balaenop- 

 tera. The only other species of the genus having black whalebone is B. borealis, but in this 

 the bristles are very fine and white. 



Weight. No attempt to measure accurately the weight of a Blue Whale seems ever to 

 have been made. An approximation, however, has been attempted by Guldberg (1907) for 

 this species, using the same method described under the Common Finback. By considering 

 the body of the whale to resemble in shape a solid composed of two cones, a longer and a shorter 

 of equal basal area, it is possible by a mathematical formula to calculate the volume of this 

 solid, and thus, by assuming a specific gravity equal to that of water, to obtain the weight of 

 such a body. To make this calculation, two measurements are needed: the total length in 



