52 BULLETIN 73, UNITED STATES NATIONAL MUSEUM. 



ridge completing nasal septum above. Mesirostral with a median groove at distal 

 end. Preniaxili:i> high at distal end, but sides nearly plane. Kostrum compressed 

 near apex, deeper than ^^-ido. (PI. 16, fig. 1 ; pi. 19, fig. 1 ; pi. 20, fig. 3.) 



Rami of mandible anchylosed together and suture partly obhterated. Teeth 

 conical, with rather short, acute tips; roots closed, short and conical; diameter, 

 25 mm. (PI. 23, fig. 1; pi. 24, fig. 2.) 



21245. Bering Island. — Nearly all sutures between maxillie and premaxillae at 

 end of rostrum, above and below, anchylosed together, but majority of others trace- 

 able. Condition of superior surface of skull very sinrilar to that of preceding, but 

 premaxillae rather low at distal end. ]\Iesirostral at distal end rather lower than 

 premaxillffi and concave superiorly; more posteriorly assuming form of a narrow 

 ridge, with a deep channel between it and premaxillie on each side. More posteriorly 

 still it widens rapidly, with a convex surface, and terminates abruptly with a trun- 

 cated end, the surface of which is concave. A deep basin around nares, as in pre- 

 ceding skull. Orifice of anterior nares far below level of nasal boss. The latter 

 largely absorbed and deeply undercut and concave in front. Nasal septum termi- 

 nating before reacliing lower end of nasals, and ridge on latter low and traversing 

 left nasal. Sides of premaxilla; at distal end very concave. Rudimentary alveolar 

 groove nearly obsolete. Rostrum blunt at apex, and about as deep as wide at 

 anterior ends of maxillte. (PI. 16, fig. 2.) 



2124s. Bering Island. — Similar to preceding, but mesirostral ossification liigher 

 than premaxillie at distal entl and convex above; less abruptly widened posteriorly 

 and posterior termination flat. Narrow, deep grooves between ossification and 

 premaxillje on each side, or, in other words, premaxilhi? more closely approximated 

 to sides of mesirostral distally. Basin around nares and conformation of the several 

 bones bordering it similar to preceding. Sides of premaxillae concave at distal end, the 

 grooves thusformed in them intruding somewhat on the maxillae, especially posteriorly. 

 Apex of rostrum very blunt, rounded off below and projecting above; deeper than 

 wide. Rudimentary alveolar groove nearly obsolete. (PI. 17, fig. 1 ; pi. 22, fig. 4.) 



Rami of mandible anchylosed together and the symphysis and suture largely 

 obhterated. Teeth very broadly fusiform; tip short and rather blunt; roots closed; 

 diameter 30 mm. 



49599. Newport, Rhode Islan/J. — Adult male. All sutures on superior sur- 

 face of skull more or less anchylosed together. Mesirostral ossification and pre- 

 maxillae all on one level near apex of rostrum, but at extreme tip mesirostral lower, 

 forming a narrow ridge with a deep groove on each side between it and premax- 

 illie. The same conformation repeated more posteriorly, but grooves deeper and 

 wider, while mesirostral maintains the same level as premaxillae. It \\ddens sud- 

 denly here, forming a broad flat-topped mass, wliich is a Httle overlappetl by the 

 premaxillie. The mass terminates suddenly somewhat behind middle of rostrum 

 with a deep concavity placed obhquely. Basin in front of the nares and conforma- 

 tion of bones composing it as in two preceding skulls. Vomer at proximal end 

 toucliing lower end of nasals, and nasal septum continued behind and above it as 

 a low ridge, composed of the inner edges of the two nasal bones and reaching up to 

 the nasal boss. Outer sides of premaxillae near distal end deeply concave. Apex of 



