240 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 



slightly excentric, forming a simple opening through the tegmen, and in 

 most of the specimens covered by a Platyceras equilatera Hall. Column 

 round and rather stout. 



Horizon and Locality. — Keokuk group; Crawfordsville, Ind. ; Hardin 

 Co., Ky. ; and Keokuk, Iowa. 



Type in the Lyon collection. 



Remarhs. — This species is Lyon and Casseday's type of the genus Goni- 

 asteroidocrimis. 



Gilbertsocrinus dispansus W. and Sp. (nov. sp.). 

 Plate XV. Figs. 2a, h, c, d. 



Syn. Qoniasteroidocrinus lyonanus — ^. A. Miller; Geo]. Surv. Illinois, Bull. 3, p. 55, Plate 4, Fig. 4. 



Of the type of Gilhertsocnnus tuherosus, but a smaller species, the arms less 

 numerous, and the calycine appendages proportionally larger. Calyx some- 

 what depressed, wider than high, truncated at the bottom, the median 

 portions deeply excavated. Plates convex except the radials, which are 

 extended into elongate nodes or obtuse spines directed obliquely downward. 



Infrabasals small, placed at the bottom of the concavity, and almost 

 covered by the column. Basals rather small for the genus ; their distal ends 

 curving upwards and forming together with the median portions of the 

 radials a rim upon which the calyx rests, while the lower portions of those 

 plates are involved in the concavity. Eadials very large, more than twice 

 as large as the costals. Costals and distichals of nearly the same size, 

 slightly projecting over the plates of the interradial and interdistichal areas. 

 Literradial areas composed of 1, 3, 3, 2, 2 plates; the middle one of the 

 second and third rows a little larger, and raised somewhat above the level 

 of the two outer ones ; the anal side not distinct. Literdistichals three, 

 longitudinally arranged. Tegmen flat, with five deep interradial depres^ 

 sions, of which the posterior one is twice as large as the others; all of them 

 oval in outline, and surrounded by a series of nodose pieces. The anal open- 

 ing occupies the inner end of the larger depression, and in perfect specimens 

 appears to be closed by a pyramid of numerous very minute pieces. The 

 smaller depressions are paved by four or five larger plates of irregular form. 

 The appendages are given off in pairs from the calyx, being for quite 

 a distance laterally connected; they are very large, slightly pendent, and 

 each pair is composed of six longitudinal rows of transverse, slightly nodose 



