BATOCRINID^. 39^ 



lower face is slightly excavated for the reception of the column. Eadials 

 large, twice as wide as long. First costals by one half narrower and shorter 

 than the radials, quadrangular; the second pentangular, wider than ■ the 

 first. Distichals two ; the upper one axillary, giving ofe from each side two 

 large pahnars, which support the arms. Arms twenty, four to each ray; 

 long, incurving and biserial ; at their bases they are somewhat angular on 

 the back, but at an inch from the calyx they gradually flatten and Increase 

 m width, reaching at half length their greatest diameter— 8 to 9 mm. — 

 which they retain a short distance, and become reduced to 5 or 6 mm. 

 at the tips. The sides of the arms are knife-like, with dentate edges, the 

 median portions considerably thickest. The arm plates increase in len<.th 

 upward from 1 to 3 mm. Interradials three, in two rows; the anal plate is 

 succeeded by three and two pieces. Ventral disk high, conical, passing grad- 

 ually mto the ventral tube, which is rather long and stout. The plates of 

 the tegmen, including those of the ventral tube, are strongly tuberculous. 



mrizon and ZocaUiy.— Keokuk group; Indian creek, Montgomery Co., 

 Ind., and Canton, Ind. 



Types in the collection of Wachsmuth and Springer. 



Eretmocrinus minor w. and Sp. (noy. spec). 

 Plate XXXVI. Figs. 10a, I. 



Calyx subpyriform, higher than wide. Dorsal cup constricted at the basi- 

 radial sutures, thence expanding moderately with straight sides to the arm 

 bases. Ventral disk semiovoid, slightly inflated at the anterior side, the pos- 

 terior side somewhat depressed. The plates of the dorsal cup perfectly flat 

 and smooth, those of the tegmen a little convex. 



Base broadly truncate, moderately high, slightly expanding downward, 

 the lower edges sharply angular, the bottom flat and hexangular. Eadials 

 nearly twice as wide as long, the upper face concave. Costals comparatively 

 large ; the first quadrangular, a little shorter and considerably narrower than 

 the radials, their upper and lower faces convex ; the second wider than the 

 first and heptangular, the sides abutting against the second row of inter- 

 brachials. Distichals three in the anterior ray, supporting two arms ; in the 

 other rays one division has three distichals, the other but two, of which the 

 upper one is axillary, giving off" a palmar from each side. Occasionally one 

 or both antero-lateral rays have four arms in place of three. Arm facets 



