BEAKED WHALES, FAMILY ZIPHIID^ TRUE. 71 



The tooth is very symmetrical, but rather more convex externally. The apex is 

 pointed, erect, and a little more convex externally than internally. (PI. 39, figs. 1,2.) 



The posterior tooth is similar to the anterior one, but much shorter and more 

 blunt, and the longitudinal furrows are about equally distinct externally and 

 internally. The cement extends nearly to the apex, which latter is rery short and 

 is directed backward. 



No. 49727. — St. George Island, Alaska; male, immature. Anterior teeth con- 

 ical, acute, somewhat unsj^mmetrical, rather more convex externally than internally. 

 The internal surface with a deep median longitudinal groove, and others less distinct 

 on each side near the base. Apex slightly inchued forward and inward, convex 

 externally, with a single longitudinal groove; nearly flat internally, ^vith, or without, 

 a groove. Base of tooth for about 17 mm. covered with longitudinal rugosities, 

 indicating that the root was about to close. It is open, however, the walls of the 

 tooth at the narrowest point being 8 mm. apart and the cavitj^ filled with dense 

 bony pulp. The anterior and posterior outlines of the teeth are irregular, being 

 convex near the base, then slightly concave, and again convex near the apex. "\Ylien 

 in the natural position, these teeth protrude about 3.3 mm., or a little more than 

 one-third their height, above the alveolus. (PI. 39, figs. 3, 4.) 



Posterior teeth lackins'. 



No. 4972-5. — Centerville beach, Cahfornia; male (?), adult. Anterior tooth 

 conical, with anterior and posterior margins as in the last. Apex considerably 

 abratled and rounded off; not inchned inward or forward. Internal and external 

 surfaces nearh' ecjually convex, but the former wth a broad median longitudinal 

 groove. Root closed, the base of the tooth for a breadth of about 30 mm. covered 

 with rounded rugosities. The inferior border slightly convex and the angles 

 rounded ofi^. Wlien in the natural position, somewhat more than one-half of the 

 tooth protrudes beyond the alveolus, and the tooth itself is inchned forward and 

 outward. (PI. 39, fig. 5.) 



Posterior tooth quite irregular in form, but the portion above the rugose base 

 or root conical. Inner surface flat and uneven. Outer surface convex and rather 

 rugose. The cement covers the whole tooth thickly to witliin about 5 mm. of the 

 apex, wliich latter is short, quite acute, and slightly directed inward. It is convex 

 externally and nearly flat internally. The basal rugosity or root is conical, thicker 

 than the rest of the tooth, and unsymmetrical, being somewhat directed backward. 

 It shows no opening below. When in the natural position tliis tooth is strongly 

 inclined forward and outward, and onlj- the tip for a length of 22 mm. protrudes 

 beyond the alveolus. (PI. 39, fig. 6.) 



No. 4-9726. — St. George Island, Alaska; female, adult. Anterior tooth conical, 

 with the tip blunt, having been so much abraded that the dentine does not extend 

 beyond the coating of cement. The tip measures 26 by 19 mm. The external and 

 internal surfaces of the tooth are about ecjually convex and somewhat rugose with- 

 out distinct furrows. The root is thicker than the remainder of the tootli and very 

 rugose. It is entirely closed below, and the inferior outline is convex. Posterior 

 tooth much compressed, conical above the root, nearly flat internally and slightly 

 convex externally. Cement coating very thick and extending to within about 5 

 mm. of the dentine apex, which latter is acute and yqvj slightly curved inward and 



