Aside from the markings mentioned, the calyx is also ornamented with depressions which look at first like borings of some kind, but which have the same granular character as the rest of the surface.
Position and locality: Carboniferous, Upper Coal Measures, Topeka, Kan., from the Osage City shales, over the Osage coal.
The type was collected by Prof. W. A. Harshbarger, in honor of whom it is named. Type now in the collection of Washburn College.
In general appearance this species is strikingly like C. craigii Worthen, but differs in the following respects: The body is not smooth but highly ornamented, and the anal piece is much larger. In all specimens of C. craigii that I have seen the body is smooth and glossy, and shows (even when apparently unworn) no indications of former surface-markings, while this species possesses both pustules and granules, the latter covering about the entire specimen. In mature individuals the interradial is much larger. Two smaller specimens, probably younger ones of this species, are figured in the accompanying plate, showing the relative growth of the calyx and interradial. In both the ornamentation is the same as described in this species. C. monticulatus Beede is from the same locality and horizon, but has long, slender arms, brachials not spinous, and the calyx is deeper. The most fundamental difference, however, is the number of arms possessed by the latter species, the number being sixteen or eighteen, while the one here described has but ten.
C. nodulifera Butts differs from this species in having a node at the upper part of each basal and also on the radials. It also has more acute and apparently longer spines. Mr. 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; the marginal sinus separating the ear from the rest of the shell broad, shallow, and ill-defined. The posterior ear is unknown. The anterior margin below the ear forms an ovate curve, which is probably continued on the ventral and postero-ventral margins. The surface of this valve is apparently marked only by stronger and fainter concentric lines except on the front and back sides, where there are radiating rows of vaulted lamellæ. It is entirely probable that these marks once extended over the entire surface, but have been worn off from the more convex portions. Judging from another specimen, the right valve is somewhat flatter than the left and quite as oblique. Posterior ear very small and obtuse; anterior ear quite large, marked by obscure, large, radiating ribs and probably vaulted lamellæ, as well as strong concentric markings; separated from the shell by a deep sulcus. 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.
Position and locality: Thin limestone, south of Dover, Kan., in Upper Coal Measures. Type in author’s collection.
This shell may prove to be a Pseudomonotis, as the critical characters are not well known. It is not liable to be confused with any other shell from the Coal Measures.