174 Trans. Acad. Sci. of St. Louis. 



convex rim for the base of the calyx and show the upper part 

 of the plates in a lateral view ; in this species the columnar 

 depression is much smaller and the subradials are compara- 

 tively shorter and only slightly convex so as to form a some- 

 what truncated base to the calyx and to show only the superior 

 angles of the plates in a lateral view. The first radials are 

 comparatively shorter and the second radials comparatively 

 longer, and the plates more convex in this species than they 

 are in Z. maniformis. The arms in this species are more 

 fusiform than in Z. maniformis. In that species there are 

 only nine arms." On page 37, in describing Z. nitidus, 

 Miller says, " Z. maniformis has proportionally a longer and 

 more globose calyx and much longer arms than our species. 

 The second radials in our species are much more constricted 

 on the sides than they are in Z. maniformis, and we are led to 

 infer, from the figure, that it had ten arms while our species 

 has only nine." In a description of Zeacrinus cylindricus 

 this statement is made: "This species has been confounded 

 with Z. maniformis by some collectors, but in that species 

 the basal plates are hidden by the column, the body is shorter, 

 and there are only nine arms, as the radial series opposite 

 the azygous area bears only a single arm." The distinguish- 

 ing features of Batocrinus prodigialis are given as follows : 

 " This species is distinguished from B. Yandelli, which it 

 most resembles, by having twenty-five instead of twenty-one 

 or twenty-two arm openings to the vault, and by having one 

 more regular interradial in each area and one or two more 

 azygous plates." 



It seems very arbitrary to make a new species because a 

 specimen has nine instead of ten arms, or has three arms on 

 the right of the azygous side instead of the left, or four 

 regular interradials and eleven azygous plates instead of three 

 regular interradials and six azygous plates, or because the 

 basals are hidden by the column, or because the basals instead 

 of being five, which is the typical number, have become three 

 or two by concrescence. With regard to the description of 

 Batocrinus prodigialis I will say that it agrees in every 

 essential point with Shumard's Actinocrinus Yandelli.* I 



* Transactions of The Academy of Science of St. Louis. 1: 7G.pl. I. f. 4,a,b. 



