PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 157. 
DESCRIPTIONS OF NEW EINVERTEBRATE FOSSIES FROM THE 
MESOZOIC AND CEN@ZOIC ROCKS OF ARKANSAS, WYOMING, COL- 
ORADO, AND UTAH. 
By C. A. WHITE. 
The fossils described in the following paragraphs are among the col- 
‘lections of the National Museum. All except one species have 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, 
Callianassa ulrichi and Spirorbis dickhauti, are embraced in a small Col- 
lection of Cretaceous fossils sent to the National Museum from near Lit- 
tle Rock, Ark., by Mr. E. O. Ulrich, of Cincinnati, Ohio. 
MOLLUSCA. 
CONCHIFERA. 
Genus PTERIA Scopoli. 
Subgenus OXYTOMA Meek. 
PTERIA (OXYTOMA) ERECTA (Sp. NOV.). 
Avicula linguiformis White, 1876 (not Shumard), Powell’s Rep. Geol. Uinta Mts., p. 95. 
Shell rather small, appearing to be nearly erect, but the axis is slightly 
oblique 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 pointed, 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 curve from 
the front all the way around to the posterior side, where it is flexed 
with a backward curve to meet the extremity of the hinge-line ; umbones 
somewhat prominent, especially that of the left valve. Surface having 
a nearly smooth appearance, but the lens reveals the presence of some- 
what regularly disposed concentric lines. 
Length of hinge-line, 32 millimeters; axial length of the shell, 26 
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 species 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. 296, pl. 5, figs. 1 and 2; but it differs in being less robust, having 
