THE WHALEBONE WHALES OF THE WESTERN NORTH ATLANTIC. 



295 



In spite of the correspondence in general propoi-tions between two Pacific 

 skulls and the Norway and Massachusetts skulls, ray associates, Dr. L. Stejneger 

 and Mi-. G. S. Miller, Jr., who examined them with me, while side by side in one of 

 the halls of the Museum, pointed out certain characters in which the two Atlantic 

 skulls appeared to them to differ from the two Pacific skulls. The principal of 

 these were (1) that the nasal processes of the maxillaj were bent toward the median 

 line much more strongly in the Pacific than in the Atlantic skulls, and (2) that the 

 orbital process of the maxillae was shorter and thicker in the former than in the 

 latter. The characters will be seen by comparing the figures on plates 22 and 23. 

 I also noted that in the Pacific skulls the vomer appeared to descend more opposite 

 the anterior end of the palatines, giving a stronger curve to the inferior jirofile of 

 the ci-anium, and that the palatines were broader posteriorly. I have endeavored 

 to bring out some of these differences in the last three measurements of the fore- 

 going table. These measurements reduced to percentages of the total length of 

 the skull are repeated below : 



BALMNOPTEBA ACUTO-ROSTRATA LAC. AND B. DAVinSONl SCAMMON. SKtTLL. 



Measurement. 



Total length of skull, straight 



Distance from inferior surface of vomer at ant. end of palatines to 

 vertex, straight 



Inner edge of proximal end of nasal process of maxilla to distal end 

 of orbital process of maxilla, straight 



Outer edge of premaxilla to distal end of orbital process of maxilla, 

 straight 



S - 



43-5 



23.6 

 26.5 



o 



m. 

 60.5 



22.7 



293 

 26.5 



S". 

 (/: o 



in. 



61.5 



25-1 



26.0 



Z2 - 



M 



o 



61.25 '^ 



24.1 



29.0 



253 



It would appear from the foregoing that the vomer is deeper in the Pacific 

 skulls, but the proportional length of the orbital pi-ocess of the maxilla does not 

 differ materially in the Norway and Pacific skidls. The breadth of this process, as 

 shown by plates 22 and 23, is greater in the Pacific skulls than in the one from 

 Norway. This greater breadth, however, is approximated in Eschi'icht's figure of 

 an adult skull from Norway {37, pi. 9, fig. 1). 



If any of these differences prove constant on examination of a larger number 

 of specimens, it will probably be the greater depth of the vomer and the bend- 

 ing inward of the nasal pi'ocess of the maxilla. As regards the latter, Eschricht's 

 and Capelliui's figures of European skulls present a substantial agreement with our 

 skulls from Norway and Massachusetts. 



' Type of B. davidsoni. " 2 '"■ added for breakage. 



