NATURAL SCIENCES OF PHILADELPHIA. 411 



the basal pieces. Opening small and irregularly circular. The arms appear 

 to consist of groups of four each ; the postero-lateral groups are not seen ; 

 their number is unknown. 



Dimensions. 



Height from base to arms "22-100 inch. 



Height from base to summit -35-100 " 



Greatest diameter '75-100 " 



Least diameter -50-100 " 



Diameter of base -35-100 " 



Height of base -05-100 " 



Geological position and locality. Collected by Dr. J. Knapp, in the same 

 beds as the preceding species. 



I have dedicated this elegant crinoid to the memory of one who loved and 

 cultivated geology, my lamented friend, the late S. A. Casseday, of Louisville, 

 Kentucky. 



Actinocrinus Meeki* n. s. Plate iv., 4 a-b. 



Calyx uniform, symmetrical, a little wider than high ; a prominent ridge 

 rises at its junction with the column, slight at first, gradually increasing in size 

 as it passes over the body along the line of the centre of the rays to the summit 

 of the third radial pieces, the whole surface of the body is elaborately orna- 

 mented by fine raised ridges slightly waving ; sometimes two are found unit- 

 ing together, especially at the external corners of the triangular figures which 

 they form ; the centre of the triangle resting on the angular notch marking 

 the union of any three adjacent pieces, the external points of the triangles 

 terminating at the centre of the pieces, except in the basal pieces, when the 

 lower point of the triangular figure terminates near the base of the pieces at 

 the column. Basal pieces three, forming a broad deep pentagonal cup, the 

 upper margins of which are slightly concave. First primary radials very large, 

 hexagonal ; the upper margin divided into three nearly equal sides, the cen- 

 tre of which supports a small quadrangular second primary radial, the centre 

 line of which is rendered very prominent by the carina marking the line of 

 the rays ; this bears a nonagonal axillary third radial, still more prominent 

 than those below. A single complete interradial field is exhibited in our spe- 

 cimen ; it consists of one large octagonal piece, supporting two small paral- 

 lelogramic pieces ; the lateral oblique margins of the third primary radials 

 also rest upon it. The form of the arms are unknown ; they appear to start 

 in groups of two each, ten in all. Column very small, round, arrangement 

 unknown. Columnar facet concave, crenulations not visible, perforation very 

 small and round. 



Dimensions. 



Height of calyx -33-100 inch. 



Height of first primary radial -37-100 " 



Whole height from base to summit of third radials -85-100 " 



Diameter at centre of first radials -80-100 " 



Diameter at summit of third radials 1-00-100 " 



Geological position and locality. Collected by Dr. J. Knapp, in beds from 

 70 to 75 feet below the black slate, Jefferson county, Kentucky, where it is 

 found associated with Caryocrinus, Eucaleptocrinus, Melocrinitis, &c. The 

 beds for several feet above and below are barren of fossils. Pentamerus 

 oblong us are quite abundant in beds from twenty to twenty-five feet 

 above. 



* I take pleasure in specifically designating this new and elegant crinoid by the name 

 of Meeki, in honor of F. B. Meek of the Geological Survey of Illinois. 



1861.] 



