FOSSILS OF THE BURLIXGTOX GROUP. 403 



lingtou beds, while the rotundatm came from the upper, and it haa 

 been found that scarcely any of the species are common to those two 

 horizons. 



Locality and position Burlington, Iowa ; lower part of Burlington 

 Limestone. .Mr. WACIISMITII'S collection. 



CVATIUM IMMTKS TKM 1 1 ).\( TYLl S. M. illld AV . 



PL -2, Fig. 15. 

 Cyathocrinite* tenuidacMu*. MEEK and WORTHEX. Proceed. Ac-ad. Xat. Sci., Phila., 1868, p. 338. 



BODY, exclusive of the free rays, deeply cup-shaped, 

 rounded below, composed of moderately thick plates for a 

 true Oyatkocrmtu. Column comparatively rather stout, 

 composed near the base of alternately thin and somewhat 

 thicker pit-res, the Litter of which project a little, and seem 

 to show a slight tendency to become minutely nodular; 

 central canal distinctly peutapetalous in the form of its 

 cross section. Base unknown, (being accidentally shoved 

 into the body with the end of the column in the specimen 

 studied). Subra dials of moderate size, those seen hexago- 

 nal. First radials somewhat larger than the subradials. a 

 little wider than long, with a general subpentagonal form : 

 facet for the reception of the second radials about one-third 

 as \vide ;ts the upper side of the plate, and excavated about 

 one-third of the way down. Second radial pieces very 

 small, wider than long, and with t\ie succeeding radials 

 curving outward. Third radial in one of the rays nearly 

 as long as wide, expanded above and contracted below, and 

 in this ray surmounted by a fourth, which, like the third 

 in each of the only two other rays seen, is a triangular 

 axillary piece, on which the arms rest, the upper angle 

 being acute, and so produced as entirely to separate the 

 arm bases, while the lateral slopes, on which the arms rest. 

 are distinctly concave. Anal piece unknown. 



Anns distinctly divergent at their origin on the last 

 radials. as well as at their succeeding bifurcations, dividing- 



