HO ALASKA GEOLOGY 



increases in diameter too rapidly to be a Turritetta, and is unlike any 

 Scala I know in the Eocene. It had a length of over 80 mm., in 

 seven whorls, and the last whorl had a diameter of over 30 mm. A 

 surmise seems warranted that the shell belongs to the group of large 

 Cerites which are known to occur both in the Alabama and the Paris- 

 ian Eocene. 



Crepidula precursor sp. nov. 



Pl. IX, fig. 3. 



Shell small, smooth, rather depressed, rounded ovate ; the beak 

 small, prominent, strongly incurved. Length 13, breadth 10, height 

 about 3.5 mm. 



Locality. Upper beds, 3374. 



The shell is flatter and the beak less spiral than in C. pileum Gabb 

 of the Tejon Eocene of California, but the characters of the internal 

 plate are inaccessible. 



? Ampullina crassatina Lamarck. 



Ampullaria crassatina LAMARCK, Ann. du Museum, v, p. 33, 1805 ; vin, pi. 



LXI, figs. 8a-b. 

 Natica mississippiensis CONRAD, Proc. Acad. Nat. Sci. Phila., in, p. 283, 



1847. 



Locality. Upper beds, 3373. 



A cast of a Naticoid shell having a very strong resemblance to the 

 Eocene species above referred to, is in the collection. It is not suffi- 

 ciently perfect to be positively identified but is probably this species. 



Natica sp. 



Locality. Upper beds, 3375. 



Fragments of a Naticoid shell in some respects recalling N. semi- 

 lunata Lea, of the Claibornian, were collected as above. 



Margarites peninsularis sp. nov. 

 pi. rx, fig. 6. 



Shell of moderate size, turbinate, with about five rounded whorls ; 

 nuclear whorls obliquely transversely striated by the lines of growth, 

 strongly mesially, spirally keeled ; keel entire and continuous but less 

 conspicuous and relatively feebler on the later whorls ; sutures deep, 

 not channelled, base rounded ; umbilicus (not accessible) ; aperture 

 subcircular, with a thin margin. Height of the shell about 12, diam- 

 eter about 12 mm. 



Localities. Upper beds, 3373, 3374, 3376. 



The specimens of this elegant shell are either crushed or so much 



