254 THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 



There is, as already stated, considerable variation, the cause of which is not entirely 

 clear. This variation affects the American specimens, which I have endeavored to 

 measure in a uniform manner, nearly as much as the European specimens, the 

 measurements of which are collected from various sources. 



The measurements of the Taranto (Italy) whale given by Gasco in the text of 

 his article (47) do not agree with measurements taken from his figures, and meas- 

 urements from the different figures do not agree with one another. Furthermore, 

 Capellini's measurements of the same specimen do not altogether agree with Gasco's. 

 Guldberg's measurements of the Iceland skulls also lack conformity to a consider- 

 able degree. While these differences may be partially due to different methods of 

 measurement, it can hardly be supposed that they all arise in that way. This 

 explanation does not serve in the case of my own measurements. 



It seems probable that the discrepancies are in part due to the shrinking and 

 warping of the various bones of the skull. The long, slender maxilla3 and pre- 

 maxillaB, the long orbital processes of the frontals and maxillae, seem quite easily 

 subject to such distortion, and in some skulls it can readily be seen that warping 

 has taken place. Again, it should be observed that most of the skulls are those of 

 young individuals, and probably exhibit differences of proportions con-elated with 

 different stages of growth. Aside from all this, however, it is undoubtedly true 

 that the species shows a considerable individual variation in proportions. 



The measurements of the length of rostrum in Guldberg's skull, received from 

 Capt. Amlie, and in Capt. Berg's No. 2, are from the base of the same and not from 

 the posterior margin of the maxilla, as in other cases. This accounts for the 

 diminished length. The measurement of the rostrum of the Taranto whale was 

 taken from Gasco's figure of the upper surface of the skull (47, pi. 2, fig. 1) ; but 

 it is obvious on comparing this figure with the side view that the rostrum is too 

 short in the former. A measurement from the side view gives about 77.2 % for 

 the length of the rostrum, which is no doubt more nearly correct. 



Gasco's measurements of the mandible of the San Sebastian whale of 1854 

 are "from the point of meeting of the internal lateral margin with the inferior 

 margin of the condyle>" which accounts in part at least for the much smaller 

 proportion. 



The other discrepancies, affecting the breadth of the skull across the orbits, the 

 length of the mandible, and the distance along the curve of the premaxillse, from 

 the tip of the nasals to the tip of the premaxillse, cannot be so readily explained. 

 As they occur in both the American and the European series, however, they cannot 

 be regarded as indicating specific differences. Doubtless, many of them would dis- 

 appear if the various specimens could be brought together for actual comparison. 



CHARACTERS OF THE VERTEBRAE. 



Measurements of the vertebras and other parts of the skeleton in a few Euro- 

 pean and American specimens are given in the following table : 



