BATOCEINID^. 401 



Eretmocrinus leucosia (Hall). 

 Plate XXXVI. Figs. 7a, b, c. 



18G1. Actbtocrinvs kucosia — Hall; Prelim. Desor. of New Criu., p. 1, and Boston Journ. of Nat. Hist., 



Vol. VII., p. 261. 

 1877. Batocrinus leucosia — S. A. Miller ; Amer. Palaeoz. Foss., p. 67. 

 1881. Eretmocrinus leucosia — W. and Sp. ; Revision Palseocr., Part II., p. 173. 

 1883. Eretmocrinus leucosia — S. A. Miller; Amer. Pateoz. Foss. (Second Edit.), p. 282. 



Sjn. Sori/crinus confragosus S. A. Miller, 1891; Geol. Surv. Missouri, Bull. I., p. 34, Plate 5, Figs. 



12 and 13. 

 Syn. Salocri/ius Blairi S. A. Miller, 1893; AdT. Sheets 18tli Rep. Geol. SurT. Lidiana, p. 39, 

 Plate 6, Figs. 7-10. 



Of the type of Eretmocrinus corhulis, but a larger species. Calyx as high 

 as wide, in large specimens somewhat wider; the rays slightly lobed at the 

 arm regions, and grooved at the anal side. Dorsal cup broadly truncated at 

 the base ; the sides uniformly spreading from the top of the basals, forming 

 a straight or very slightly concave line to the bases of the arms. Plates 

 moderately convex, without ornamentation, the suture lines grooved and 

 quite distinct. 



Base short, projecting outward, and forming a salient, trilobate rim with 

 sharp lower edges ; the lower face perfectly flat except in the median part, 

 which to one third the diameter at the bottom is slightly excavated; the 

 axial canal large for this genus, and pentangular. Eadials large, once and 

 a half as wide as long, the upper face concave. First costals quadrangular, 

 and small as compared with the radials ; the second wider and pentangular, 

 unless they are touched by the second row of interbrachials, which is excep- 

 tionally the case. Distichals two, short ; followed in four of the rays by two 

 exceedingly short, transverse palmars, which support the arms ; in the ante- 

 rior ray, which has no palmars, directly by the arms. Arm facets very large, 

 directed slightly upwards, and arranged in groups. The interspaces between 

 the rays considerably wider than those between their subdivisions, and 

 somewhat grooved, especially at the anal side. Arms eighteen, massive, 

 long, incurving, and biserial from the calj'x up ; they are given off in piair,?, 

 and the two arms of each pair are suturally connected to the height of the 

 third arm plate. For quite a distance from the calyx, the arms are evenly 

 rounded at the back, but they grow flatter toward the tips, and increase 

 some little in width. The arm plates are moderately short, and every fifth 

 piece in both series is provided with a lateral spine. The spines near the 

 calyx are quite short, but those in the upper regions attain a length of 4 mm. 



51 



