BEAKED WHALES, FAMILY ZIPHIID^ TEUE. 51 



alveolar groove distinct distally. Proximal end of vomer anchylosed with anterior 

 face of nasals and reaching up to nasal boss, which has a sharp median ridge com- 

 pleting nasal septum superiorly. Anterior face of nasal boss slightly concave on 

 each side of median line. (PI. 14, fig. 2; pi. IS, fig. 2; pi. 20, fig. 2; pi. 21, fig. .3.) 



Rami of mandible anchylosed together at symphysis and suture largely obliter- 

 ated. Teeth slender, cylindrical, rugose, rather blunt; roots closed; diameter 13 

 mm. (PI. 24, fig. 3.) 



22069. Bering /sZaTwZ.— Adult female ? All the sutures about as in preceding 

 specimen. Mesirostral ossification distinct, rounded, extending from base of rostrum 

 nearly to apex, but disappearing before reaching line of anterior ends of maxillag. 

 Its upper surface below that of premaxillse. Premaxillas approximated, and right 

 premaxilla with an angular process near base of rostrum overlapping mesirostral 

 ossification. Premaxillfe at base of rostrum, anterior nares, proximal end of vomer, 

 and nasals as in preceding skull. Apex of rostrum moderately acute, broader than 

 deep. Rudimentary alveolar groove shallow. (PI. 15, fig. 1.) 



Rami of mandible anchylosed together and suture largely obliterated. Teeth 

 somewhat fusiform, blunt; roots closed; diameter, 14 mm. (PI. 22, fig. 3.) 



83991. Benng Island. — Similar in all respects to preceding, but mesirostral 

 ossification a little less well developed. 



22874. Bering Island. — Entirely similar to two preceding, but premaxillae a 

 little curved out from mesirostral ossification and left premaxilla opposite maxillary 

 notch rather strongly inclined, nearly vertical. Anterior face of nasal boss dis- 

 tinctly concave. (Skull defective.) 



21246. Bering Island. — Sutures as in three preceding skulls, ilesirostral 

 ossification distinct and rounded, but much below level of premaxOlffi. Rostral 

 portion of premaxillsB narrow and widely divergent toward base of rostrum, leaving 

 mesirostral entirely exposed. Right premaxilla on a line with maxillary notches 

 strongly concave and sunk below level of maxillae. Left premaxilla vertical, with 

 a broad groove. Right premaxilla remains low and concave proximally, the pos- 

 terior end being then abruptly turned upward and reaching level of vertex. Orifice 

 of anterior nares on a level with lower end of nasal boss, and vomer resting against 

 anterior face of nasals, which latter have a median ridge continuing nasal septum, 

 but with a slight vacuity between the two. Rudimentary alveolar groove nearly 

 obliterated. Outer sides of premaxillte at distal end strongly concave. Rostrum 

 rather acute, about as deep as wide opposite distal ends of maxilla;. (PI. 15, fig. 2.) 

 20993. Bering Island.— Adult male? (Type of Z. grebnitzkii) . Majority of 

 sutures open, but maxilla; and premaxilla; anchylosed together above and on the 

 sides. Premaxilla; approximated anteriorly, but diverging posteriorly. Mesirostral 

 ossification well developed, reaching level of premaxill;?; anteriorly rather narrow 

 but a Uttle broader near middle of rostrum, where it is beveled off abruptly. Behind 

 this point premaxilla; strongly concave, nearly vertical and widely separated, form- 

 ing a large and deep basin, in the bottom of which the vomer appears as a broad, 

 irregular bony surface. Bottom of basin much below level of surrounding parts. 

 Orifice of anterior nares much below level of nasal boss. Vomer reaching lower end 

 of nasals. Anterior face of latter strongly concave, with only a moderate median 



