BATOCEINIDiE. 379 



Basal cup trilobate, more than twice as wide as long, flat at the bottom, a 

 little contracted at the ii^jper end. Eadials more than four times as large as 

 the costals, a little wider than long. Costals two, all of nearly equal size, 

 but the first quadrangular, the second pentangular; wider than long. Pal- 

 mars in two ranges ; the upper supporting the free arms, except those next 

 to the anal side, which are axillary and sustain two post-palmars ; there 

 being five arms to each posterior ray, and twenty-two to the species. The 

 anal plate is followed by two rows of three plates each, above which the 

 post-palmars meet in lateral contact. At the other interradii the first inter. 

 brachials, which are almost as large as the radials, are followed by one or two 

 small pieces arched over by the palmars. Arm openings directed liorizon- 

 tally, arranged at equal distances around the calyx, with a slight depression at 

 the posterior side. Arm structure not known. Ventral disk hemispherical, 

 a little shorter than the dorsal cup ; composed of rather large, tuberculous 

 plates of nearly the same size. Anal tube almost central, wide at the base ; 

 its length not known. 



Horizon and Locality. — Upper Burlington limestone; Burlington, Iowa. 

 (A rare species.) 



Tt/pe in the Museum of Comparative Zoology. 



Batocrinus tuberculatus W. and Sp. (nov. spec). 



Plate XXriII. Figs. 10a, b. 



A very graceful species, rather below medium size. Calyx higher than 

 wide, gradually expanding from the basals to the top of the distichals, and 

 thence more rapidly to the arm bases. Plates of the dorsal cup tuberculous, 

 with well defined sharp nodes in the centre, those of the brachials forming a 

 sort of interrupted obscure ridge. 



Basal cup distinctly trilobate, deeply depressed at the interbasal sutures, 

 flanging outward at the lower end, and depressed at the bottom. Eadials 

 about as wide as long, with a large transverse node. Costals small, both 

 together very little more than one third the size of the radials ; the first 

 smaller than the second, quadrangular ; the ujDper pentangular. Distichals 

 two, followed by three palmars, which support the free arms. Arm bases 

 directed horizontally, forming an iminterrupted line around the ca]yx. Arms 

 twenty, equidistant, short, rather delicate, flattening at their upper ends, and 

 curving inward; their lateral margins indented, and their backs lined by two 



