BEAKED WHALES, FAMILY ZIPHIID^ TKUE. 27 



the premaxillse. The end of the beak consists of the consolidated mass of the pre- 

 maxillfe and mesirostral ossification, the whole being convex above and below, but 

 flat on the sides. The ossification has a deep median groove, which reaches to 

 within 95 mm. of the tip of the beak. 



It will be seen that the conformation of the upper surface of the beak is quite 

 different from that of bidens or any other species. 



The maxillary foramina are large and directed forward, and have a distinct 

 broad channel in front of them. In the Oregon skull the right foramen is single, 

 but the left divided into two. The premaxillary foramina are a little behind the 

 maxillary foramina. The distance between the maxillary foramina is less than 

 that from the median line to the anteorbital notch. In bidens it is much greater. 



Lateral aspect (PI. 9, figs. 1, 2). — A most noteworthy feature of the skull when 

 viewed from the side is the great length between the orbit and the maxillarj- notch, 

 which far exceeds that found in bidens and other species, being equal to the length 

 of the orbit itself. The latter is about as long as tiie temporal fossa, which is some- 

 wiiat flattened above, as in europxus. The outline of the supraoccipital is straight 

 and nearly vertical. Tiie zygomatic is more massive even than europxus and is 

 especially thick below. The inferior outline of the beak is convex proximally as in 

 europseus and layardi. There is no basirostral groove, the edges of the maxillae 

 being very thick in front of the maxillary notch. Over the orbit the maxillae are 

 thick and beveled, but not raised as in howdoini. 



Ventral aspect (PI. 6, figs. 1, 2). — The beak is convex in the proximal half, much 

 as in europseus, but farther forward is concave, except in the median line, where 

 there is a narrow ridge formed proximally by the vomer, which in the type skull 

 appears as a narrow lozenge 60 mm. long. In the adult Oregon skull it is anchylosed 

 with the premaxillse. The maxillte extend to within 107 mm. of the end of the beak. 

 The under surface of the beak is much more like that of europseus than of bidens. 



A narrow strip of the palatines extends around the base of the pterygoids in 

 front, but the two strips do not meet in the median line. In the type-skull they 

 do not extend inside the pterygoids. The expanded anterior end of the malar is 

 very long and also forms the bottom of the maxillary notch, which is the case in 

 europseus but not in bidens. The inferior borders of the pterygoids are convex 

 anteriorly, as in europseus, and are continued laterally, so that the sinus is deep as in 

 that species. The lachrymal is very long, the free margin having a length of 55 mm. 

 The posterior margin of the zygomatic process is concave, rather than convex as in 



bidens. 



The tympanic bulla does not differ materially from that of bidens in size or 

 shape, as far as can be judged from the figures given in Van Beneden and Gervais' 

 Osteography (plate 26, figs. 4, 4fl). The periotic is similar in size to the same bone in 

 bidens, but the posterior end is more narrowly pointed and the anterior end is 

 much lower, relatively. In europseus, as far as can be determined from tiie material 

 at hand, the form and size of the earbone is similar to that of stejnegen, but in the 

 latter the anterior margin of the tympanic bulla is more naarly transverse and the 

 posterior inferior groove is curved. (PI. 35, fig. 2.) 

 24765— Bull. 73—10 3 



