248 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
interradial depressions, surrounded by small nodose plates of rather irregular 
arrangement. Orals tuberculous; anus excentric. 
Horizon and Locality. — Hamilton group; Ontario Co., and Thedford, 
Ontario. 
Types in the New York State Cabinet of Natural History at Albany, and 
in the Canada Survey Museum at Ottawa. 
THYLACOCRINUS Ocsterr. 
1878. Ognzert; Extr. du Bull. Soc. Géol. de France (sér. 3) Tome VII., p. 578. 
1879. Zrrret; Handb. d. Paleont., Vol. I., p. 375. 
1881. W. and Sp.; Revision Paleocr., Part II., p. 207 (Proceed. Acad. Nat. Sci., Phila., p. 381). 
Calyx large, plates convex; anal interradius distinct from the others; 
arms arranged in groups of four or more. Infrabasals five, small. Basals 
five, heptagonal; their upper faces truncated, and each plate supporting an 
interradial. Radials followed by two costals, and these by 2X2 distichals, 
which in turn support within the calyx several brachials of a third, and 
sometimes of a fourth order. Arms heavy, long, simple throughout, and 
biserial. Interbrachials numerous, arranged longitudinally im series of two 
or three, with additional plates at the anal side. Interdistichals very numer- 
ous, in rows of one or two; interpalmars also represented. Construction of 
the tegmen and position of the anus unknown. Column, so far as observed, 
pentangular with re-entering angles. 
Distribution. — Devonian; France, and Hamilton group; Western New 
York. 
Type of the genus. — Thylacocrinus Vannioti Oehlert. 
Remarks. — Thylacocrinus differs from Rhodocrinus in having interdis- 
tichals and interpalmars; the former being very rarely, the latter never, 
preserved in that genus. It also differs in the arrangement of the plates 
of the anal side, in having four or more primary arms to the ray in place of 
two, and in that the arms are large and simple throughout. 
Thylacocrinus Clarkei W. and Sp. (nov. spec.). 
Plate XIII. Figs. 11a, b. 
Calyx apparently globular; the plates very gradually and uniformly de- 
creasing in size upwards, Infrabasals small, and forming a pentagon with the 
points of the angles slightly projecting beyond the column; column attach- 
