NATURAL SCIENCES OF PHILADELPHIA. 165 



Locality and position. Six miles southeast of Anna, Union Co., Illinois ; from 

 the St. Louis division of th*e Subcarboniferous series. Collected by Mr. Henry 

 Engelmann. 



PENTREMITES (GRANATOCRINUS?) granulosus, M. & W. 



Body small, subglobosus, base deeply concave, particularly in the middle, 

 and not visible in a side view. Radial plates a little longer than wide, about 

 two-thirds as long as the entire body, and tapering from above to the base, 

 each divided by the narrow pseudo-ambulacral areas, down almost to the very 

 base ; lateral margins moderately promiuent. Interradial pieces subtrigonal, 

 or with a fourth obscure angle in the middle below; longer than wide, and 

 each narrowing from below to the summit, where they are perforated by two 

 minute openings. Anal piece of the same size and form as the interradial, 

 with its opening circular, and comparatively large, its outer margin being pro- 

 tected by a small, rather pointed node. Pseudo-ambulacral areas narrow, or 

 sublinear, rather impressed, and each with a distinct longitudinal, linear, 

 mesial furrow ; pore pieces from twenty-five to thirty. Surface marked by 

 comparatively distinct granules, most strongly defined on the interradial and 

 anal pieces, where they sometimes show a tendency to arrange themselves in 

 transverse lines parallel to the lower margin. 



Height of body, 0-22 inch; breadth of do. 0-23 inch. Breadth of pseudo- 

 ambulacral areas, 0-05 inch. 



Not having at hand a specimen or figure of the type of Troost's Granatocrinus, 

 we are not quite sure this form belongs to that group, though we have no 

 doubt in regard to the propriety of separating such species from the typical 

 forms of Pentremites. Our species has somewhat the general form and appear- 

 ance of P. Roemeri of Shumard, (Missouri Report, pi. b, figs. 2a, 2b, 2c and 2d,), 

 but differs too widely to render a detailed comparison necessary. 



Locality and position. Keokuk division of Subcarboniferous series, near War- 

 saw. Illinois. 



POLYZOA. 



Genus EVACTINOPORA, M. & W. 



EVACTINOPORA RADIATA, M. & W. 



The interesting fossil upon which we propose to found this genus and 

 species is entirely silicified, and, as seen from below, presents the form of a 

 regular eight-rayed star, the rays being slender, and nearly equalling in length 

 the diameter of the nucleus. In a side view, however, it is seen to be regu- 

 larly rounded in outline below, while the slender rays are observed to be pro- 

 duced upwards in the form of thin vertical laminae, which converge to the 

 centre over the nucleus. The specimen is not in a condition to show whether 

 or not there is a central axis extending all the way up, but there probably is. 

 The rays are thickest below, and taper gradually upwards on their outer margins, 

 which are beveled or carinated all the way down to where they meet at the 

 middle of the under side. Within, they each pass abruptly into a thin lamina, 

 which is poriferous on both sides, and extends to the middle over the nucleus. 



The pores are circular, with a slightly prominent margin, and regularly dis- 

 posed nearly in quincunx, at intervals about equalling their own diameter, or 

 sometimes less. They only exist in the thin portion of each ray, while the 

 thicker outer and inferior portions seem to be nearly or quite solid. 



We are not able to determine satisfactorily whether this was a free or an 

 attached Bryozoon; but if attached, the stem or point of attachment was pro- 

 bably very small. 



Greatest transverse diameter to the extremity of the rays, 0-90 inch ; do. of 

 nucleus between the rays, 0-35 inch ; thickness of the outer margin of each ray 

 near the nucleus, 0-10 inch ; diameter of pores about 0-02 inch. 



1865.] 



