INVERTEBRATES. 263 



This species will be at once distinguished from all of the others yet known, by 

 its more compressed elongated form, and the lateral arrangement of its cells, 

 as well as by the crenulated character of its surface striae. 



Locality and position : Spurgen Hill, Indiana; St. Louis group of Lower 

 Carboniferous series. 



.RADIATA. 



EOHINODERMATA. 



CRINOIDEA. 

 f 



Genus DICHOCRINUS, Munster. (See page 167.) 



PI. 19, fig. 2 a, 2b, 2c. 



Dichocrinas constrictus, Meek and Worthen, Sept., 1860. Proceed. Acad. Nat. Sci., 

 Philad., p. 381. 



Body small, oval or obovate, approaching subglobose, rounded 

 above and below, and rather distinctly constricted just below 

 the middle, composed of comparatively thick plates, which are 

 apparently smooth, and joined by linear sutures. Base large, 

 or forming about one-third of the body, twice as wide as high, 

 and more or less concave in the middle of the under side; each 

 of its pieces having five obscure angles above, with very 

 slightly concave margins between, for the reception of the suc- 

 ceeding range of plates ; columnar facet very small and round. 

 First radial plates higher than wide, a little unequal, with an 

 oblong-subquadrangular outline; one of them having a fifth 

 very obtuse angle at the middle of the under side ; sinus in 

 the upper margin of each, for the reception of the second 

 radials, rounded, rather shallow, and from one-third to one- 

 half the breath of the upper side of each plate. Anal piece 

 slightly larger than the first radials, and like them narrowing 

 and curving inwards at the summit, subpentagonal in outline. 

 (Other parts unknown.) Length to the top of the first radials, 



