214 Field Columbian Mijseum — Geology, Vol. i. 



shells several feet in thickness, having a meagre arenaceous matrix, 

 are traceable for miles. Farther north in Kansas they still form the 

 most abundant types. 



OSTREA BELOITI, n. sp. 

 (PI. XXV, Figs. 7 and 8. Mus. No. P 5944.) 



Shell thin, oblong, moderately capacious, and possessing more 

 than ordinary symmetry. Beaks are long and sharply pointed; fit- 

 ting closely. Lower valve deep; area broad, triangular, with rounded 

 borders, possessing a slight depression in the posterior-central por- 

 tion; posterior border, rounded ; anterior border, pointed ; dorsal 

 border, slightly concave, nearly straight; ventral border, convex. 



Upper valve, flat or slightly convex transversely; in general out- 

 line it is very similar to the lower valve; area much the same, perhaps 

 a little shorter. Muscular impression in both valves, sub-central and 

 indistinct. Surface not rough or but little imbricated. 



Dimensions — Length, 45mm.; width, 25mm.; height, 8mm. 



The species occurs in the Lincoln Marble horizon of the Benton. 

 It is not abundant and has been collected from two localities only. 

 The specimen here described was collected from an outcrop on the 

 Solomon river in the Kansas area. 



FASCIOLARIA sp. 

 (PI. XXV, Figs. 1 and 3. Mus. No. P 5941.) 



Shell a little more than moderate size, stout fusiform; spire con- 

 sisting of three rather convex volutions. The body whorl large and 

 possessing in the central region a flat area; whorl merging into a 

 rather short canal which is slightly curved; last whorl (body) and 

 canal more than equalling the length of the spire. Surface ornamen- 

 tation not distinct in specimen, hence the difficulty of determining 

 the species. 



Several fragmentary specimens which probably belong to the 

 genus Fasciolaria were collected by the writer from the septaria of 

 the Blue Hill shales (Benton). The material is in such a condition 

 as not to warrant specific determination. They are figured and men- 

 tioned only for the purpose of making our literature as complete as 

 possible and with the hope that in the future better material may 

 be obtained through the suggestion of the presence of such forms. 



