“ Margin from the beak around the posterior to near the middle of the shell is a regular ovate curve, antero-ventral margin somewhat produced but rounded, extending obliquely toward the beak until the deep byssal sinus is reached. Ornamentation as in the other valve. In this specimen it seems that the radiating rows of scales covered the entire surface before being worn away. Length, 36 mm.; height, 32 mm.; hinge, 17 mm.; thickness, about 5 mm. ”

“ Butts makes no mention of finer surface-markings. The Topeka specimen is from a much higher horizon.
Aviculopecten subequivalvus, n. sp. Plate V, figs. 3, 3a. Shell thick, moderately large, subequivalvular, rather convex, quite oblique, ears well developed. The hinge is nearly straight, the beak does not project, the angle of divergence of its sides is about eighty to ninety degrees. The left valve, exclusive of the ears, is ovate; anterior ear well developed, obtusely angular, marked only by strong lines of growth; the rise from the ear to the body of the shell is abrupt ”

“ A specimen from the Topeka limestone, Upper Coal Measures, at Topeka, Kan., shows the spires with the apex of one of them pointing almost directly forward toward the anterior end of the shell, turned through a horizontal angle of about ninety degrees from its normal position, while, as nearly as may be determined from the specimen as cut, the apex of the other one is directed toward the median line of 156the pedicle valve just in front of the hinge. ”

“ Four of the twelve specimens studied were somewhat compressed, but it so happens that three of these approach the normal type very closely, while the fourth does not vary from it greatly. Those showing greatest variation have not been subject to any visible external deformation. ”

“ Fig. 8. This figure probably shows the brachial side of specimen, while fig. 8a is the opposite side. Fig. 9. Brachial view. Fig. 10. The pedicle view of a specimen, and fig. 10a the brachial side of the same. Fig. 11. Brachial valve nearly ground away, to show spire. The sickle-shaped structure is probably the base of the opposite spire. Beede’s collection. Fig. 12. Specimen with brachial valve largely broken away. All specimens but No. 11 in collection of University of Kansas.
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PLATE VI.
TRANSCRIBER’S NOTES Silently corrected obvious typographical errors and variations in spelling. ”