PKOCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 157 



DESCRIPTIONS OF NEW IIVVEKTEBRATE FOSSII^S FROI?I TFTE 

 MESOZOIC AIVE> €ENOZOIC RO€KS OF ARKANSAS, Wl'OIVIINC}, C'OJIL- 

 ORADO, AIVE> UTAH. 



By C. A. TVHITE. 



The fossils described in the following paragraphs are among the col- 

 lections of the National Museum. All except one species h.ive been 

 selected for description from among the collections that were made 

 under the auspices of the surveys formerly in charge, respectively, of 

 Professor Powell, Dr. Hayden, and Captain Wheeler. Two of them, 

 CalUanassa ulrichi and Sjxirorbis diclhauti, are embraced in a small Col- 

 lection of Cretaceous fossils sent to the National Museum from near Li"-- 

 tie Kock, Ark., by Mr. E. O. Ulrich, of Cincinnati, Ohio. 



MOLLUSCA. 

 CONCHIFERA. 



Genus PTERIA Scopoli. 



Subgenus OXYTOMA Meek. 



Pteria (Oxytoma) erecta (sp. nov.). 



Avicida I'mgnifcrmis White, 1876 (not Sliinnard), Powell's Rep. Geol. Uiuta Mts., p. 95. 



Shell r:ither small, appearing to be nearly erect, but the axis is slightly 

 obliijue to the hinge-line ; both valves convex, but the right one less 

 convex than the left ; hinge-line long, much longer than the axial length 

 of the shell ; posterior wing large, its extremity acutely angular and 

 moderately prominent; anterior wing comparatively large, prominent, 

 obtusely j^ointed, defined from the body of the shell by a sinus or furrow 

 in both valves, the direction of which forms a slightly obtuse or nearly 

 right angle with the hinge-line ; front, exclusive of the anterior wing, 

 nearly perpendicular the margin forming a nearly regular curv'e from 

 the front all the way around to the posterior side, where it is flexed 

 with a backward carve to meet the extremity of the hinge-line ; umbones 

 somewhat prominent, especially that of the left valve. Surface having 

 a nearly smooth ai)pearance, but the lens reveals the presence of some- 

 what regularly disposed concentric lines. 



Length of hinge-line, 32 millimeters; axial length of the shell, 2G 

 millimeters. (Museum No. 8771.) 



This shell was formerly referred by me {loc. cit.) to the Avicula lingui- 

 formis of Shumard, but it differs from that sp:^3ies by having larger 

 wings, a much longer hinge-line, and a much less oblique axis. It may 

 be compared with P. (0.) salinensis White, Proc. U. S. Nat. Mus., vol. 

 ii, p. 29G, pi. 5, figs. 1 and 2; but it differs in being less robust, having 



