Vol. 4] 



Osmont. — Areas of California Neocem . 



1)1 



to make this portion of the shell appear almost fiat. The poste- 

 rior end is pointed, and that portion near the hinge concave. 

 The basal margin is nearly straight, and parallel to the hinge 

 line. The ribs number '25 or lib', and are narrow and without 

 grooves. The growth lines tend to produce a headed effect. 



The specimen displayed in figs. 2, 2a and 2b appears to 

 bridge over the differences between those of figs. 1 and 3. Tt has 

 26 ribs. 



Occurrence and Associated Fauna. — The specimen shown in 

 figs. 3a and 3b is labelled Santa Monica. In the Geology of Cali- 

 fornia Whitney states that the fossiliferous sandstones of Santa 

 Monica have yielded the following fauna : 



Neverita recluziana Desh. Cerithidea sacrata Cj>r. 



Twritella ocoyana Conr. Cardita subtenta Conr. 



Trochita costellata (.'our. Mytilus edulis Linn. 



Turritella ocoyana alone shows this horizon to be lower Mio- 

 cene. 



The specimen shown in figs, la and lb was collected by Eld- 

 ridge from a limestone series below the silicious shales of the Dev- 

 il's Den region, in Kern County. Here were also found: 

 Astrodapsis tumidus Bern, or possi- Pecten sp., very large. 



bly Clypeaster brewerianus Rem. Ostrea sp. 

 Pecten pabloensis Conr. 



The form shown in figs. 2. '2a and 26 is from an unknown 

 locality. 



A. microdonta seems to be a very variable, and is. so far as 

 known, confined to the Miocene. 



A RCA TRILINEATA Conrad. 

 Plate 9, Figs. 4— 4c. 



Area trilineata Conrad. Pac. R. R. Reps., 1854-5, Vol. VI, p. 70. 

 PI. II, fig. 9. 



Area sulcicosta Gabb. Palaeontology Cat., Vol., II, p. 31, PI. 9, fig. 53. 

 Area schizotoma Ball. Trans. Wag. Vr. Inst., Vol. 3, Pt. 4, p. 659. 



Description. — Conrad's description is as follows: "Trape- 

 zoidal, somewhat produced, inequilateral, ventricose, ribs 22-24. 

 scarcely prominent, square, wider than the intervening spaces, 

 ornamented with three impressed or four raised lines; disk con- 

 centrically wrinkled; summits prominent: beaks approximate. 

 Length 3 inches. 



