Talbot — New York Helderbergian Crinoids. 23 



the infrabasals, generally so fused as to show no suture lines on 

 the outer surface, although they are often seen on the inner 

 side. Upper margin scalloped for the attachment of the radials 

 and the anal plate. Radials five, large, rectangular, the upper 

 margin excavated slightly for the attachment of the brachials 

 and the lower curved to fit into the concave upper margin of 

 the basals. An anal plate half as wide as the radials and a 

 small plate above it furnish all that is known of the anal area. 

 Ventral surface unknown. Arms known in only one species, 

 E. sacctdus, where they consist of very short transverse plates 

 and bifurcate several times, but show no trace of pinnules. 

 Genotype, E. pocilliformis Hall. 



Edriocrinus pocilllformis Hall. Plate IV, figures 1-6. 



Edriocrinus pocilliformis Hall, Nat. Hist. N. Y., Pal., vol. iii, 1859, p. 121, 

 pi. v, figs. 8-12.— Meek and Worthen, Geol. Rept. 111., vol. iii, 1868, p. 370, 

 pi. 7, figs. 5a and 5b. — Wachsmuth. and Springer, Rev. Palaeoer., Pt. Ill, 1886. 

 p. 266; Proc. Phila. Acad. Nat. Sci., vol. xxxviii, 1887, p. 190.— Keyes^ 

 Geol. Surv. Mo., vol. iv, 1894, p. 221, pi. xxx, fig. 7. 



Amended specific description. — Infrabasals present but so 

 fused that their number is uncertain. Height from one-half to 

 two-thirds that of the cup as ordinarily found. Basals five, 

 completely fused with each other and with the infrabasals or 

 distinguished from the latter as a narrow protruding band. 

 Suture lines sometimes apparent on the interior. Upper mar- - 

 gin scalloped for the attachment of the radials and the anal 

 plate. Height about half that of the infrabasals. Radials five, 

 often as high as the infrabasals and basals combined, and, like 

 them, fused to form a part of the cup. In most instances, how- 

 ever, the suture lines between the radials are plainly discernible. 

 As a rule, the union between the radials and basals is not so 

 strong as that of basals with infrabasals ; and the cup is gener- 

 ally broken off at the top of the basals. Since in no specimens 

 are brachials preserved, the union of brachials with radials must 

 have been still weaker. Anal plate as high as the radials, but 

 only half as wide. Radials and anal gently convex, sloping in 

 all directions from the center of the plate. Arms and ventral 

 disk unknown. The attachment scar is visible on a number of 

 specimens, and in some is a short distance up on the side of the 

 cup, rather than on the bottom. 



Horizon and locality. — Throughout the New Scotland lime- 

 stone in Helderberg Mountains. 



Cotypes in the American Museum of Natural History. 



Order, Camerata Wachsmuth and Springer. 



Family, Thysanocrinidce Wachsmuth and Springer. 

 Genus, Thysanocrinus Hall. 

 Thysanocrinus arborescens n. sp. Plate I, figure 2 ; text-figure 1. 

 Although, in America, no members of this genus have been 

 reported above the Niagara, a number of crinoids that must 



