BATOCRINID^. 449 



Horizon and Localiti/. — Upper Burlington limestone, Burlington, Iowa. 



Types in the Museum of Comparative Zoology. 



liemarks. — This rare and beautiful species is readily recognized by the 

 peculiar form of its base, the large nodes upon the radials and interbrachials, 

 and the flat plates in the upper part of the dorsal cup. The nodes upon the 

 radials hang downward, and their extremities reach almost to a line with the 

 lower end of the basals. 



Macrocrinus gemmiformis (Hall). 

 Plate XXXVI. Fig. 8. 



I860. Aetinocrimis gemmiformis — Hall; Suppl. Geol. Eep. Iowa, p. 23 (Photogr., Plate iJ, Fig. 6, 1872, 



N. X. State Museum, Bull. I.). 

 1873. Batocrinits {Bretmocrinus ?) gemmiformis — Meek and Woethen; Geol. Eep. Illinois, Vol. V., 



p. 368. 

 1877. Batocrinus gemmiformis — S. A. Miller; Catal. Palseoz. Toss., p. 72. 

 1881. Eretmocrinus gemmiformis — W. and Sp. ; Revision Palaeocr,, Part II., p. 173. 

 1890. Bretmocrinus gemmiformis — S. A. Miller; Nortli Amer. Geol. and Pateont., p. 243. 



A small and delicate species. Calyx a little higher than wide. Dor.sal 

 cup truncate at the bottom ; the sides moderately and uniformly rising to 

 the arm bases ; higher than the ventral disk. Plates elevated ; the radials 

 covered with long transverse nodes or obtuse spines, and similar elongate 

 nodes, but circular in outline, are formed on the second costals, the first 

 interbrachials, and the anal plate ; the distichals and palmars angular on the 

 back, forming distinct ridges. 



Basals produced into long spreading extensions, which overhang the 

 upper part of the column, giving to the base a decidedly trilobate outline. 

 Eadials large, a little wider than long. Costals less than half the size of the 

 radials, almost as long as wide; the first quadrangular; the second pent- 

 angular. The anterior ray has 3X2 distichals ; the four other rays have in 

 one division two small distichals, followed by two palmnrs, in the other three 

 distichals. There are fourteen arms to the .species, exceptionally fifteen or 

 sixteen, the odd number occurring in the antero-lateral rays. The ujjper 

 brachials are in contact laterally except on the anal side, where they are 

 separated by an elongate piece, which connects with the plates of the disk. 

 Structure of arms unknown. Anal plate higher than the radials, supporting 

 three large plate.s, and these from two to three small ones ; the interbrachials 

 at the four regular sides consist of two to three plates. Ventral disk hemi- 

 spherical ; the plates large and sharply nodose. The posterior oral forms at 



