7C Art. 6.— M. Yokoyama : 



Living. — West const of America from Puget Sound down to 

 the Strait of Magellan. 



Genus Crepidula^ Lamarck. 



76. Crepidula orbella, Yokoyama. 



Pl. IV. Figs. 22, 23. 



Shell small, thin, somewhat variable in shape being roundly 

 quadrate to roundly ovate in outline, flatly convex; apex small, 

 spiral, posterior, marginal; surface with concentrical rugose lines 

 of growth; septum posterior, concave on both sides of a blunt 

 median ridge; the greatest diameter 7 millim. Three specimens. 



A. Adams described a species of Crepidula from Goto (Kyushu) 

 under the name of C lamellosa (Ann. Mag.. 180:2, p. 297) without 

 any figure. It seems to resemble this fossil form, hut Adams says 

 that the dorsal side of the shell is lamellar and imbricate, so that. 

 the two can not be quite identical. 



Fossil occurrence. — Naganuma Zone (Naganuma). 



Family Naticidae. 



Genus Natica, Adanson. 



77. Natica janthostoma, Deshayes. 



P.e. V. Flos. 3, 4. 



Natica janthostoma. Deshayes, Revue Zool., p. 361. Libchkb, Jap. Meeresconch., I, p. 81. 

 Dünker, Index Moll. Mai*. Jap., p. Gl. Phtlippi in Syst. Conch. Cab. Mart. n. Cbemn., vol. 

 TJ, Abt. 1, Natica u. Amaura, p. 53, pl. 8, fig. 8. Pilsbry, Cat. Jap. Moll., p. 71. 



Natica clausa rar. jathostoma. Middendorff, Mal. Ross. II, p. 209. Schrenck, Moll. 

 Ainurl. u. d. Nordjap. Meeres, p. 373. Tryon, Man. Conch., vol. VIII, p. 31, pl. 19, fig. 89. 



Natica clausa. Tokunaga, Foss. Env. Tokyo, p. 17, pl. I, fig. 31. 



The shell is globose, somewhat higher than broad, consisting 

 of about six whorls, which are often flattened below the suture. 

 The growth-lines are distinct, crossed in some instances b}^ very 

 tine spiral lines most conspicuous below the suture. The aperture 

 is semilunar with the posterior corner subangular and the anterior 

 rounded. The callus is semi-circular and flat, and closes the 

 umbilicus, but always with a more or less deep groove surrounding 

 it on the rounded side. 



