52 BULLETIN 73, UNITED STATES NATIONAL MUSEUM. 



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

 end. PremaxilliB high at distal end, but sides nearly plane. Kostrum compressed 

 near apex, deeper than wide. (PI. 16, fig. 1 : pi. 19, fig. 1 ; pi. 20, fig. 3.) 



Rami of mandible anchylosed together and suture partly obliterated. Teeth 

 conical, ^v^th rather short, acute tips; roots closed, short and conical; diameter, 

 25 mm. (PI. 2.3, fig. 1 ; pi. 24, fig. 2.) 



21245. Bering Island. — Nearly all sutures between maxillse and premaxillte at 

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

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

 premaxillae rather low at distal end. Mesirostral at distal end rather lower than 

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

 ridge, \\-ith a deep channel between it and premaxillw on each side. More })osteriorly 

 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 reaching 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 maxilhe. (PL 16, fig. 2.) 



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

 than premaxillffi at distal end and convex above; less aln-uptly widened posteriorly 

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

 premaxilla^ on each side, or, in other words, premaxilla^ more closely approximated 

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

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

 gi'ooves thusf ormed in them intruding somewhat on the maxilla, 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. Neivport, Rhode Island. — Adult male. All sutures on superior sur- 

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

 maxillfe 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- 

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

 wider, wliile mesirostral maintains the same level as premaxilla. It widens sud- 

 denly here, fornung a broad flat-topped mass, wliich is a Httle overlapped by the 

 premaxillaj. The mass terminates suddenly somewhat behind middle of rostrum 

 wdth a deep concavity placed obhquelv- Basin in front of the nares and conforma- 

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

 touching 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 



