BATOCRINID^. 429 



rather large for the species, the nodal joints projecting and rounded at the 

 edges. 



Horison and Locality. — Upper part of Keokuk group, Ci'awfordsville, 

 Ind., Keokuk, Iowa, and Pike Co., Mo. 



Type in the Illinois State collection, Springfield. (The specimen figured 

 on Plate XLV'I. is the type of " Batocriims Gurleyi" R. and H.). 



Dizygocrimis montgomeryensis, var. unibrachiatus W. and Sp. (nov. var.). 



Plate XXXIII. Figs. 5, a, h, c. 



The above name is proposed for a form very similar to D. montyomeryeiisis, 

 but having single arms in place of double ones. It also closely resembles 

 D. hiturhinaius ; but the specimens are larger, the dorsal cup is proportionally 

 shorter, the arms are longer, less tapering, and placed farther apart. 



Horison and Locality. — Associated with D. montgomeryensis in the Upper 

 Keokuk beds, near Keokuk, Iowa. 



Types in the collection of Lisbon A. Cox, and Wachsmuth and Springer. 



Dizygocrinus mutabilis W. and Sp. (noT. spec). 

 Plate XXXV. Figs. 8, 9, 10, 11. 



Calyx biturbinate to subglobose ; the dorsal cup a little higher than the 

 ventral disk ; the plates of the former flat, and the surface without ornamen- 

 tation or other markings ; suture lines slightly grooved. 



Basals forming a low basin, hexangular in outline. Radials fully twice as 

 large as both costals together ; the upper face concave. First costals very 

 short, linear, the sides convex ; the second pentangular with obtuse upper 

 angle. Distichals larger than the costals, increasing in width upward. They 

 are represented by two ranges of three plates in the anterior ray, and also in 

 one of the divisions in the other four rays ; while in the opposite division 

 the second piece is axillary, and supports 2X2 palmars, thus giving rise to 

 fourteen arm openings, which bear either single or double arms. Among 

 our seven specimens there is but one in which all the arms are paired. In 

 the six others the paired arms are indiscriminately intermingled with single 

 ones, and in three of these specimens the right antero-lateral ray consists of 

 two pairs, of which one pair rests over the suture line of two adjoining pal- 

 mars and not upon a distichal. Arms rounded, long, incurving, and com- 

 posed of rather long transverse pieces. Pinnules flat at the surface, their 

 joints rather short. Regular interbrachials three. The anal plate is consid- 



