166 GEOLOGICAL SURVEY OF THE TERRITORIES. 
ten plications on each side of the mesial sinus, which correspond in char- 
acter with those upon the other valve; the postero-lateral portions of the 
valve rounded into the area, which is very short and its limity ill-defined ; 
foramen moderately large, triangular, and nearly equilateral. 
Length from ventral beak to front, 28 millimeters; greatest breadth, 
32 millimeters; g greatest thickness, both valves together, 18 millimeters. 
This species was originally described from an imperfect example which 
was obtained from the Warsaw limestone near Alton, Il. Among a 
collection of fossils obtained by Mr. William Gurley, from equivalent 
strata at Spergen Hill, Ind., is a more perfect example, which has served 
as the basis for the description and illustrations herein given. 
Position and locality—Subearboniferous strata, Warsaw division, 
Alton, Il., and Spergen Hill, Monroe County, Indiana. 
(MOLLUSCA VERA.) 
CONCHIFERA., 
Genus ANTHRACOPTERA Salter. 
ANTHRACOPTERA POLITA (Sp. NOV.). 
Plate 42, figs. 5 a and D. 
Sheil rather small, aviculoid, moderately gibbous, height greater than 
the breadth from front to rear; test thin; valves subequal; hinge mar- 
gin short, straight, terminating posteriorly in a somewhat obtusely 
angular wing, but not extending in front of the beaks; basal and front 
margins forming a nearly regular curve from beneath the beaks to the 
postero-basal extremity, which is more narrowly rounded; between that 
extremity and the posterior angle of the wing the margin is slightly 
concave; umbo prominent, or having the appearance of being somewhat 
inflated; beak elevated a little above the hinge line; the ear is distinct, 
but no well-defined auricular groove separates it from the body of the 
shell in either valve. Surface having a smooth aspect, but it is marked 
by numerous fine lines of growth, which-are plainly visible under a lens. 
Height from base to hinge line, 20 millimeters; length from umbo to 
posterior basal extremity, 24 millimeters. 
This shell seems evidently referable to Anthracoptera of Sulter, 
although nothing is known of the character of its hinge or of its interior 
markings. It differs too materially from any known species to need 
detailed comparison. 
Position and locality —Coal-measure strata, Major’s Mili, Vermiliion 
County, Ul, where it was discovered by Mr. William Gurley. 
Genus ASTARTELLA Hall. 
ASTARTELLA GURLEYI White. 
Plate 42, figs.6 a@ and 6. 
Astariella gurleyt White, 1878, Proc. Acad. Nat. Sci. Philad., p. 35. 
_ Shell small, not very gibbous, subtetrahedral in outline; anterior end 
truncated from the beaks obliquely downward and for ward to about 
a i 
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=a eo) EBS 
