38 



Subradials a little longer than wide, with an angular prominence 

 just above the middle of each plate, extending from the center to 

 the upper margins. 



Kadials about half as large as the subradials, length and width 

 about equal, triangular below, the angles fitting into the depres- 

 sions between the subradials. They are all surmounted by a small 

 semi-circular arm facet, from which a shallow groove extends to a 

 central opening m the summit. 



Just above the summit of one of the subradials, and in the lateral 

 angles of two of the radial plates, there appears to have been a cir- 

 cular opening rather larger than the arm facets, which is now filled 

 with stony matter, and whether this is an anal opening, or an acci- 

 dental break in the test of the body, is a question to be determined 

 from additional material. Columnar facet scarcely larger than that 

 for the reception of the arms. 



Arms and column unknown. 



We take pleasure in dedicating this unique fossil to Mr. W. H. 

 Adams, of Elmore, Peoria county, who found it on section 13, town- 

 ship 11 north, range 6 east, in Peoria county. 



It is from about the horizon of coal No. 8 of the lower Coal 

 Measures. 



ARTICLE U. 



Corrections and proposed new names for species described in the 

 geological reports of illinois, under names that were pre- 

 occupied ; and descriptions of two new species of fossil 

 shells from the coal measures of illinois and kansas. 



By a. H. Worthen. 



The following species of fossil shells were described by Meek and 

 Worthen in the published volumes of the Geological Survey of Illi- 

 nois, under names that were subsequently found to be pre-occcupied 

 by other authors ; and the following corrections are now proposed 

 for these forms : 



MocUolopsis orthonota, M. and W., 1868, Geol. Surv. of 111., Vol. 3. 

 The name proposed is Modiolopsls rectaformis. 



Modiolopsls sdmasuta, M and W., 1870, Geol. Surv. of III., Vol. 3. 

 Name now proposed, Modiolopsis CarroUensis. 



Orthoceras anmdo-costatwm, M. and W., 18G'2, Geol. Surv. of 111., 

 Vol. 6. Name now proposed, Orthoceras Eandolphensis. 



Platyceras suhundatuni, M. and W., 1866, Geol. Surv. of 111., Vol. 3. 

 Name now proposed, Platijceras snhsiuuosa. 



Pleurotomaria conoidcus, M. and W., 1866, Geol. Surv,, of 111., Vol. 

 5. Name now proposed, Pleurotoviaria cotioformis. 



Platyostoma tumida, M. and W.. 1860, Geol. Surv. of 111., Vol. 2. 

 Name now proposed, Platyostoma Grayinllensis. 



A shell, figured and described in Vol. 3, Geol. Surv. of 111., page 

 536, pi. 19, lig. 1, 2, belonging to the genus Lithophaya, was referred 



