EETEOCRINID^. 183 



Tnterradial spaces deeply impressed ; composed of numerous minute 

 pieces without definite arrangement; they rest upon the basals, separating 

 the rays from their bases up. Anal interradius wider than the four others ; 

 divided longitudinally by a row of folded plates, which like the radials have 

 a prominent ridge upon the outer surface, and a groove at the inner floor. 

 The ridge ends in a small protuberance containing the anal opening, which 

 points upwards. Interdistichal spaces also deeply depressed, and filled by 

 irregular, minute plates, which like those between the main rays pass imper- 

 ceptibly into the disk. Yentral disk comparatively flat, composed through- 

 out of very small pieces ; orals being unrepresented, and the disk ambulacra 

 subtegminal. 



Column quadrangular, with pentangular central canal, the angles of 

 which are directed interradially. 



Distrihidion. — This genus, so far as known, is limited to the upper part 

 of the Hudson River group of Ohio. 



Ti/pe. — Xenocriniis penicillus Miller. 



RemarJcs. — We place in this genus Glyptocrinus Baeri Meek, which, as we 

 have discovered, has a quadrangular stem and four basals. Xeiiocrinush the 

 only monocyclic genus in which interradials come in contact with the basals 

 at all sides, but we doubt if its interradials separated the rays as completely 

 as in the case of the Rhodocrinidse. In a specimen of X. Baeri from the 

 collection of Mr. I. H. Harris (Plate IX. Fig. be), in which portions of the 

 inner floor are exposed, it is plainly seen that the lower ends of adjoining 

 radials touch each other, and after a careful study of the structure we are 

 inclined to believe that the small accessory pieces, which seem to separate 

 the radials, rest upon the lower outer margins of the plates, and not between 

 the plates. 



Xenocrinus penicillus Miller. 

 Plate IX. Figs. 6a, h. 



1881. S. A. Miller; Joarn. Cincin. Soc. Nat. Hist., Vol. lY., p. 73, Plate 1, Pig. 3; and ibid., p. 176, 



Plate 4, Pig. 6. 

 1883. W. and Sp. ; Amer. Journ. of Sci., Vol. XXV., p. 266, and 1885, Revision Palseocr. Part III., 



p. 96. 



A small species. Calyx elongate, once and a half as high as wide, ob- 

 conical at the lower end, then rising almost vertically to the free arms ; the 

 radials and brachials highly elevated, folded lengthwise wdth rounded back ; 

 the interradial spaces deeply impressed, the plates somewhat nodose. 



