ACEOCEINID^. 807 



short joints, which near the calyx, at intervals of five to six, are interrupted 

 by longer and somewhat wider plates. 



Horizon and Locality. — Kaskaskia group; Grayson and Pulaski Cos., Ky. 



Type'm. the Yandell collection at Louisville. 



Remarks. — The fragmentary specimen from the same horizon of Pope 

 Co., Ills., for which Hall proposed the name Acrocrinus urncrformis, is in all 

 probability identical with this species. It has preserved only the basals and 

 a few rings of the intercalated plates, which are not sufficient for accurate 

 comparison. 



Acrocrinus Wortheni Wachsmuth. 



Plate LXXX. Figs. 10a, I. 



1882. 'Wachsmiith-; Bull. I. Illinois State Museum Nat. Hist., p. 41; and Geol. Rep. Illinois, Vol. VII., 



p. 343 (with diagram). 

 1885. W. and Sp. ; Revision PalaBocr., Part III., p. 124. 



This species was described from a single specimen, of which only the 

 dorsal cup is preserved. This, however, is in excellent preservation, and, 

 notwithstanding its small size, every plate can be readily traced. The cup is 

 calycxdate, broadly truncate at the bottom, whence it curves rather abruptly 

 upward, its width slightly decreasing to the upper end. The entire length 

 of the specimen is but 5 mm. by i.\ mm., its greatest width, and 4 mm. across 

 the top of the radials. The surface of the plates is without ornamentation, 

 but sufficiently convex to bring out the suture lines. 



Basals comparatively large, restricted to the truncated lower face of the 

 calyx, and not visible from a side view ; they are separated from the radials 

 by six rings of plates, which increase in size upward. There are twelve 

 plates in the first ring, triangular in outline, which are so minute that it 

 requires a good magnifier to discover them. Another row of twelve some- 

 what larger plates constitutes the second ring. The latter are joined by 

 their lateral fiices, the lower angles resting between the sides of the preced- 

 ing plates. Five of them are placed radially, seven interradially, one at each 

 regular interradial side, and three at the anal side. Ten of the plates are 

 hexagonal, the middle one of the anal side and the anterior radial one hep- 

 tagonal and truncated above. The third ring consists of fourteen pieces, 

 larger than the preceding ones, but less regular in their arrangement ; 

 twelve of them alternate with the plates of the second ring, and the two 

 others rest upon the truncated upper faces of the two larger heptagonal 



