BEAKED WHALES, FAMILY ZIPHIID^ TKUE. 13 



notches (straight) is 312 mm., while in the largest adult among the European speci- 

 mens this distance is only 260 mm., and in the thoroughly adult Nantucket specimen 

 282 mm. 



SKULL. 



The Atlantic City and Long Branch skulls also agree in numerous other details 

 of structure in addition to the foregoing, the more important of which will now be 

 mentioned. Unless otherwise stated, the type-skull, as shown by Van Beneden and 

 Gervais' figures,*^ also presents the same peculiarities in contrast with M. bidens. 



Dorsal aspect (PI. 2, figs. 1 and 2). — The premaxillaj are more depressed imme- 

 diately in front of the blowhole than in M. bidens, which, witii the prominence of 

 the maxillary ridges, makes this whole region appear strongly concave. The blow- 

 hole is narrower absolutely and also relatively to the breadth of the expanded 

 proximal ends of the premaxillie, so that while in bidens the breadth of the blowhole 

 is much more than one-tliird the breadth across tlie proxunal ends of the premaxill^, 

 in europseus it is considerably less than a third. Both premaxillse are much con- 

 stricted on the sides of the blowhole and the effect is heightened by the greater 

 expansion of the proximal ends of the former. Tliese ends do not fit closely against 

 the adjoining edge of the maxilliB as in bidens, but leave a transverse vacuity, or 

 trough, which is especially noticeable in the type-skull. The anterior end of the 

 malar bone occupies tlie bottom of the maxiUary notch and a small portion of it is 

 visible from above, while in bidens it does not extend up into the notch at all from 

 the inferior surface ami is not visible from above. The posterior margin of the 

 maxillse is more squared in europieus tlian in bidens. 



The margins of the beak, formed by the maxillae, instead of being straight, are 

 somewhat emarginate a little posterior to the middle of the length and somewhat 

 convex anterior to it, which gives the contour of the beak, seen from above, a 

 different shape from that of bidens. In the tyi)e-skull of europseus the mesirostral 

 ossification appears to be higher at the proximal end than the premaxilhT, and 

 distally extends to the end of the beak. In bidens it is lower than the premaxillje 

 and, in the Nantucket skull at least, ends anteriorly at the same point as the vomer, 

 or, in other words, much behind the end of the beak. It would appear from the 

 statements of Sir William Turner, A'an Beneden and Gervais, Grieg, and others, 

 that the mesirostral ossification never reaches the end of the beak in bidens, but it 

 does in grayi, Tiaasti, densirostris, and many fossil sjDecies, as well as in europieus. 



Lateral aspect (PI. 8, figs. 1, 2). — The temporal fossaj are a httle longer than 

 the orbit in europseus, but a little shorter than the orbit in bidens; in the former the 

 superior margin is flat or a Httle concave, rather than convex. The exoccipital 

 extends in an angle farther forward in europseus, and the suture between it and the 

 zygomatic is, in consequence, less nearly vertical than in bidens. The premaxiUffi 

 at the sides of the blowhole are nearly horizontal, so that their superior surface is 

 little seen from this aspect, while in bidens they slope downward, so that tlie whole 

 of the superior surface is visible. Tlie high maxillary ridge, situated behind the 

 anteorbital notch, is very noticeable from this point of view, as it shuts off a 



o Ost6ographie, plate 24. 



