182 PALEONTOLOGY OF ILLINOIS. 



RHODOCRINUS NANUS Meek and Worthen. 



PI, XVI, Fig. 4. Specimen with arms from the anterior side. 



PL XVII, Fig. 15. Another specimen from another side. 

 1866, Meek and Worthen, Proc. Acad. Nat. Sci. Phila., p. 254. 



1868, Geol. Surv. Ill, Vol. III. p. 476, PL 18, Figs. 2 a, b. 



This species was described by Meek and Worthen in Vol. Ill, 

 of these Reports, p. 470, PI. 18, Fig. 2 a, b, from a single speci- 

 men without arms. It was found by one of us in the Kinder- 

 hook beds near Burlington, just above the oolitic layer, but by 

 mistake it was stated in the description to be from the Lower 

 Burlington. It remained unique until the Le Grand discoveries 

 brought to light a number of specimens, which apparently be- 

 long to the same species, and as they present the characters of 

 the species more fully, we have thought it best to redescribe it 

 briefly. 



Rhodocrinvs nanus is nearest allied to A. kirbyi, from 

 which it is distinguished by its more globose form, more slender 

 arms, and these composed of longer and more uniform pieces, 

 as well as by the ridge-like series of anal plates. In the Le 

 Grand beds this species is readily identified by its color, which 

 is invariably light. 



Calyx subglobose, sides regularly convex, except in specimens 

 with protuberant basals, in which the sides are nearly vertical. 

 Base truncate, slightly impressed. 



Underbasals small, projecting but little beyond the column. 

 Basals large, sometimes protuberant, the cup resting on their 

 lower edges, which are rounded and form a low rim around the 

 shallow basal depression. 



First primary radials nearly as large as the basals; second 

 and third about equal, and one-third the size of the first radials. 

 Secondary radials 1x2x5, followed by about five rounded quad- 

 rangular brachials of uniform size. 



Arms bifurcating on the fifth joint, and the inner branches of 

 the ray once again on the third joint, with an occasional bifur- 



