196 tROCEEDtNGS OF THE ACADEMY OP [1886. 



The following species have been described : 



1865. Catillocrinus Bradleyi, Meek and Worthen, Proc. Acad. Nat. Sei. Phila., p. 



;'.42; also 1868, Geol. Rep. Illinois, vol. v, p. 504, PI. 14, figs. 10 a, 6. Keo- 

 kuk limest. Crawfordsville, Ind. 

 ISjO. Catillocrinus Tennesseae Troost (Type of the genus). List Crin. Tenn., 

 Proceed. Aiuer. Assoc, p. 60. Sliumard, 1868, Trans. Acad. Sci. St. Louis, 

 vol. ii, p. 358. Keokuk limest.. Button-mould Knob, near Louisville, Ky. 



1866. Catillocrinus Wachsmuthi, Meek and AVorthen. (Symbathocrinus [Nemato- 



crinus] Wachsmuthi.) Proceed. Acad. Nat. Sci. Phila., p. 251. Catillo- 

 crinus Wachsmuthi, 1868, Geol. Rep. 111., iii, p. 465, PI. 18, fig. 5. Upper 

 Burlington limest. Burlington, Iowa. 



MYCOCRINUS Schultze. 



1866. Schultze, Monogr. Echin, Eifl. Kalk., p. 223. 

 1879. Zittel, Handb. d. False outologie, voL i, p. 380. 



Schultze supposed that Mycocrinus had no arms, but his own 

 figures and description indicate the contrary. The radials are 

 provided close to the peripliery, and in Iront of the ambulacral 

 grooves, with well developed articular facets, pierced by trans- 

 verse slits. 



Mycocrinus resembles the last described genus very closely, but 

 differs in the bipartite basal disk, the greater symmetry and regu- 

 larity in the arrangement of the radials, and in the general form. 

 We offer the following : 



Revised Generic Diagnosis. Calyx in form of a mushroom, 

 constructed of two series of plates, the upper series forming the 

 thallus, the lower the stalk. The plates are massive, of very 

 irregular form, and without ornamentation. 



Basals two, large, unequal ; one of them twice as large as the 

 other. They are very heavy and form a distinct, subglobose, 

 knob-like body, slightly truncate below for the reception of the 

 column. Its upper side rises to form a low five-sided pyramid, 

 near the outer margins of which there are twelve narrow slits 

 parallel to the edges. Two of the sides have three slits each, the 

 three others two each. 



Radials five, resting with their inner edges upon the angular 

 margin of the basal disk, each plate facing one of the five sides of 

 the pyramid. They spread broadly outward from the edge of 

 the basals, and extend far beyond their outer margins. Two 

 of the radials are of equal width, much larger than the rest. 

 These two are separated from one another at one side by two 

 equal, much smaller plates, at the other by a single plate some- 

 what larger than the two others. The single plate is more than 



