BATOCKINID^. 473 



defined next to the margin of the plates, but are indistinct, or disappear 

 altogether, in the middle portions. Color of specimens lighter than in the 

 last species. The calyx up to the arm regions is obconical, wider than high, 

 and a little convex at the sides. 



Basal cup short, projecting laterally, and forming a rim which is slightly 

 excavated at the bottom. Eadials somewhat shorter than those of Aoro- 

 crimis immaturus, the costals proportionally longer. The distichals vary in 

 number; in the anterior ray there are 2X2 in the calyx, followed by 

 free arm plates; the other rays have two in one division, but only one 

 in the other, which is axillary and followed by palmars ; exceptionally in 

 the posterior rays the first is axillary in both divisions, but generally only 

 that next to the anal side. Arms fourteen, rather stout, rounded on the 

 back, and quite long ; they are composed of two or three cuneate plates, 

 which interlock and are followed by two series of transverse pieces, nnited 

 by parallel sutures. Interbrachials six in three ranges ; the first plate is 

 large and extends to the top of the costals. There are three much smaller 

 plates in the second range, and two in the third, the latter on a level with 

 the arms. Anal area very wide, the first plate as large as the radials, the 

 three succeeding plates fully equal in size to the single plate at the four 

 regular sides, the middle plate being a little the largest. These plates are 

 followed by numerous smaller ones, which take part in the ventral disk. 

 Construction of the tegmen and position of the anus unknown. Of the 

 column nearly three inches are preserved in one of the specimens ; it is de- 

 cidedly tapering, the nodal joints high and projecting. So far as observed, 

 the stem changes but little its general habitus. As it decreases downward 

 in width, the internodal joints retain nearly the same proportions to the 

 adjoining nodal ones as close to the calyx. 



Horizon and Locality. — Same as last. 



Types in the collection of Wachsmuth and Springer. 



Aorocrinus parvibasis W. and Sp. 



Plate XLV. Figs. Sa, h. 



1890. Dorj/crlims parviiasis — W. and Sp. ; Geol. Eep. Illinois, Vol. Till., p. 177, Plate 17, Figs. 7 and 



9, 9a. 

 1890. Dorycrinxspamiasis — S. A. Millek; N. Amer. Geol. and Pateont., p. 240. 



A small species. Calyx oblate-spheroidal, excavated at the bottom. 

 Dorsal cup in form of a basin that i-ests upon the basals and portions of 



60 



