36 PROCEEDINGS OF THE ACADEMY OF 



teeth in the other valve, would also favor the conclusion that it is not a true 

 Chonetes. Nevertheless, we prefer to place it provisionally in that genus, un- 

 til specimens can be obtained showing the dorsal valve, with the muscular 

 impressions and other generic characters. Should it be found, as we believe 

 it will, to be a new generic type, we would suggest for it the name hogramma 

 (tiros, equal; }?*/*/*, a line), in allusion to the remarkable equality of the con- 

 centric lines of the surface. 



To whatever genus our shell may really belong, it is evidently very closely 

 allied, even specifically, to a form figured by Mr. Davidson from the Carbon- 

 iferous limestone of Scotland, in his valuable Monograph of the British Car- 

 boniferous Brachiopoda, vol. ii, part v, pi. lv, fig. 13. Mr. Davidson referred 

 his shell, with much doubt, on the authority of Dr. De Koninck, to Chonetes 

 concentrica, of the latter author. We fully concur with Mr. Davidson, how- 

 ever, in the opinion that it is distinct from Prof. De Koninck's* species, as it 

 is much longer, and instead of being marked with only 12 to 13 large concen- 

 tric ridges, has about 37 regular, more concentric lines. In our species there 

 are about twice the number of lines seen on that figured by Mr. Davidson, in 

 specimens of the same size ; and as this character is remarkably uniform in 

 all our specimens, we cannot believe it otherwise than a specific difference. 



Locality and position. Upper Coal Measures, Marion County, Illinois, where 

 it occurs associated with nearly all the fossils in the Upper Coal Measures of 

 Kansas and Iowa, and in those in Nebraska referred by Profs. Marcou and 

 Geinitz to the Permian. 



Spikifkr fastigatcs, M. and W. 



Shell attaining a rather large size, moderately convex, very transverse, or 

 distinctly more than twice as wide as long ; greatest breadth on the hinge 

 line ; lateral extremities very attenuate and acutely pointed in young speci- 

 mens, but becoming more obtuse in larger individuals ; front and anterior 

 lateral margins broadly and rather regularly rounded. Dorsal valve nearly 

 as convex as the ventral ; beak depressed, somewhat incurved, and scarcely 

 projecting beyond the hinge line; area of rather more than usual breadth for 

 that of a dorsal valve, and arched with the beak; mesial fold commencing at 

 the beak scarcely larger than one of the ribs on each side of it, but increasing 

 gradually in breadth and prominence to the front, where it is occupied by 

 about six to eight costye, which, however, coalesce into one or two at the 

 beak. Ventral valve regularly convex over the central region, and somewhat 

 compressed toward the lateral extremities ; mesial sinus commencing narrow 

 and very small near the beak, and widening and deepening gradually to the 

 front, where it is occupied by about eight depressed, rounded costa?, which, 

 like those on the fold of the other valve, coalesce with those on each side 

 and with each other, so as to leave but one that extends quite to the beak ; 

 beak rather depressed and not projecting much beyond the hinge line, arched 

 or moderately incurved; area rather narrow, and extending with almost per- 

 fectly parallel margins, quite out to the lateral extremities of the hinge, marked 

 by the usual transverse and vertical striae ; foramen wider than high, rather 

 large, and extending close up under the rather flattened apex of the beak. 



Surface ornamented by depressed, rounded, bifurcating or trifid, more or 

 less fasciculated costs, about five of which, on each side of the mesial sinus and 

 fold, are larger than the others, and divide before reaching the front, so as to 

 form as many fasciculi of two or three ribs each, the furrows between which 

 are less strongly defined than those between the bundles. Toward the lateral 

 extremities some eight or ten smaller, simple, obscure costae, that do not 

 reach the beaks, may also be counted, on each side of each valve, gradually 

 becoming obsolete near the ends. Crossing the whole, fine obscure, undulat- 



* It is due to Prof. De Koninck that we should state that it was only doubtfully he re- 

 ferred the English specimen to his species. 



[April 



