136 PROCEEDINGS OF THE ACADEMY OF 



rays again divide once more, making seven rays to some of the arms and 

 eight to others. The arms are rounded, very gradually tapering, and each 

 composed of a double series of alternating pieces, supporting tentacles within. 

 The sutures separating the first radials, as well as those between them and the 

 base, are rather distinctly grooved, as well as those between the succeeding 

 pieces, up to the last bifurcation of the free arms. 



The surface of the first radial plates is rather concave, and between the pro- 

 jecting margin of the sinus above, and the marginal grooves ; the concave 

 space being sometimes marked by very faint traces of small radiating corruga- 

 tions. Very small longitudinal obscure striae or wrinkles, can also be seen by 

 the aid of a magnifier on the outer side of the arms, above the last divisions. 



This species is allied to P. corrugatus of Owen and Shumard, but differs in the 

 style of its surface markings, being in fact nearly entirely smooth. It also 

 differs in having a distinct marginal groove along the sides and base of its first 

 radial plates. Its body is also proportionally higher to the summit of the first 

 radials. 



Locality and position. Burlington, Iowa. Burlington Limestone. Collec- 

 tion of Mr. Charles Wachsmuth. 



Genus CYATHOCRINUS, Miller. 1821. 



Cyathocrinus Wachsmuthi. Body depressed, obconical, or subturbinate. 

 Base of moderate size, low, and distinctly pentagonal, the angles formed by 

 the extremities of the plates a little incurved. Columnar facet covering about 

 one-third to one-fourth of each basal piece. Column obscurely pentagonal 

 near the base, the angles being rounded ; central perforation comparatively 

 large and pentagonal. Subradial plates five or sis times as large as the basal 

 pieces, about as long as wide, three of them hexagonal, and two on the anal 

 side heptagonal, all indented or incurved at the sides and at the upper angles. 

 First radials larger than the subradials, unequal in size, and wider than long ; 

 all heptagonal, in consequence of the truncation of the superior lateral angles 

 apparently for the reception of small interradials, each having the angles below 

 distinctly indented, and upper side truncated, and moderately concave for the 

 reception of the succeeding plates. Second radials very short or nearly linear, 

 and about two-thirds as wide as the first. Third radials generally a little 

 narrower, and longer than the second, and apparently triangular in form. 

 Sub-anal piece comparatively large, quadrangular, and indented at the angles ; 

 first true anal plate larger than the sub-anal piece, heptagonal in form, resting 

 upon a very short upper truncated side of one of the subradials, and connect- 

 ing on each side with the first radials ; its right inferior sloping side also rest- 

 ing against the sub-anal piece. The arms after dividing on the third radials, 

 are strong and rounded on the outer side ; one of the divisions in each of the 

 rays, excepting anterior one, bifurcates again on the fourth piece. All the 

 divisions and subdivisions are rounded, gradually tapering, and composed 

 each of a single series of pieces as long as, or a little longer than wide, and 

 giving off at intervals of two or three pieces alternately on opposite sides, 

 rather strong jointed lateral divisions, which extend obliquely outwards and 

 bifurcate several times. The surface seems to be merely irregularly granulose. 

 On examining it closely, however, traces of very small radiating slightly raised 

 lines are seen on the subradial and radial plates, as well as extending up the 

 principal divisions of the arms. 



We take pleasure in dedicating this species to Mr. Charles Wachsmuth, of 

 Burlington, Iowa, to whom we are indebted for the use of the specimen de- 

 scribed. 



Locality and position. Burlington, Iowa. Burlington Limestone of the 

 Lower Carboniferous series. 



Genus BTJRSACRINTJS, N. G. 



(0vp<ra a purse ; x/wvoc a lily, in allusion to the purse-like form of the typical 



species, as seen with its arms folded together.) 



[June, 



