WHITE.] _ TRIASSIC FOSSILS. 109 
Position and locality.—Triaxsic strata; member A of the section at 
locality No. 1, Southeastern Idaho, where it is associated with <Avicu- 
lopecten idahoensis and other species. Collected by Dr. A. C. Peale. 
TEREBRATULA AUGUSTA Hall & Whitfield 2 
Associated with the preceding species at locality No. 1, is another 
species of Terebratula which may perhaps prove to be a new form, but 
it is too nearly like 7. augusta Hall & Whitfield and 7. millipunctata 
Hall to warrant the application of a new specific name. The latter is 
a well-known Upper Coal Measure species of the Mississippi Valley; and 
the former is reported from Jurassic strata at Shoshone Springs, Au- 
gusta Mountains, Nevada. 
CONCHIFERA. 
Genus AVICULOPECTEN McCoy. 
AVICULOPECTEN ? PEALEI White. 
Plate 32, fig. 4 a. 
Aviculopecten pealei White, 1879, Bull. U. S. Geol. Sur. Terr., vol. v., p. 169. 
Shell, exclusive of the ears, subovate in marginal outline; obliquity 
of the axis to the hinge-line backward, and forming with it an angle of 
about 70 degrees; hinge-margin not quite as long as the greatest trans- 
verse diameter of the body of the shell. Left valve moderately convex, 
the convexity being nearly uniform except in the umbonal region, where 
it is, as usual, oreatest ; beak moderately prominent, incur ved and ele- 
vated slightly above the hinge-margin; anterior ear moderately large, 
prominent, extending as far forward as the front margin of the shell, 
distinet from the body of the shell, but not separated from it by a dis- 
tinct auricular furrow ; its antero-inferior border convex sloping back- 
ward to a moderately deep, angular byssal notch; front margin of 
the valve regularly convex in outline; antero-basal margin also convex, 
but not quite so much so as the front; postero-basal margin somewhat 
abruptly rounded up to the nearly straight posterior margin. Posterior 
ear moderately large, but not quite So “prominent as the anterior ear, 
moderately distinct from the body of the shell. 
Surface marked by numerous raised radiating lines and small coste, 
the latter being less numerous than the former, and differin g from them 
only in being larger; all of them being slightly undulating in their di- 
rection from the umbo towards the margins. Near the margins three 
or four of the lines occupy each of the spaces between the coste. 
‘Both ears are marked by radiating raised lines similar to those onthe 
body of the valve, but they are more numerous and finer on the poste- 
rior ear than on the anterior. No ribs appear on the ears, and the lines 
referred to are not quite so distinct as they are on the body of the valve. 
Crossing the radiating lines and coste there are numerous fine but - 
distinct concentric lines, and some larger wrinkles of growth. Right 
valve and hinge unknown. 
Height from. base to beak, 37 millimeters; antero-posterior diameter 
of the body of the shell, 33 millimeters ; leng th of hinge-margin, 28 
millimeters. 
The hinge of this shell being unknown, it cannot with absolute cer- 
tainty be referred to Aviculopecten, but its form and external characters 
