PLATYCRINID&. 661 
Horizon and Locality. — Base of Lower Burlington limestone ; Louisi- 
ana, Mo. 
Type in the collection of Mr. Rowley. 
Remarks. — From the small size of the specimen, and the structure of the 
ventral disk, we are inclined to believe that it represents a very young form 
of P. burlingtonensis. 
Platycrinus quinquenodus Waitt. 
Plate LX XI. Figs. 14a, b, ¢. 
1862. Wuttz; Proceed. Boston Society Nat. Hist., p. 18. 
1881. W. and Sp.; Revision, Part IL., p. 74 (Proceed. Acad. Nat. Sci. Phila., p. 248). 
Syn. P. planobasalis Rowiey and Haru, 1891; Kansas City Scientist, p. 97, Plate 2, Fig. 1. 
Of moderate size. Calyx rather rapidly and evenly spreading from the 
truncated base to half the héight of the ventral disk; the lower brachials 
directed almost horizontally. Ventral disk as high as the cup, distinctly 
convex, extended outward to the top of the distichals, and forming well de- 
fined lobes, which give to the calyx a sharply quinquelobate outline. Plates 
of the dorsal cup heavy and without ornamentation, except that the base 1s 
marked by five rounded nodes, interradially disposed and directed down- 
ward. Basi-radial and interradial sutures channeled. | 
Basal cup deep, fully two thirds the length of the radials, truncated at 
the bottom, the sides gradually spreading. Radials as long as wide, wider 
above than below, the median portions below the facets much the thickest ; 
the lower faces almost straight, the upper angles deeply truncated and 
forming with the corresponding sides of adjoining plates deep notches; the 
notch of the anal side considerably deeper, extending down to fully one 
third the length of the plates. Facets semicircular, facing almost horizon- 
tally, the upper end not notched, or only a very little. Costals pentangular, 
the upper faces concave. Distichals nearly twice as wide as long, those of 
the same ray in sutural contact laterally, the upper ones axillary. Structure 
of arms unknown. Plates of the disk nodose, except the interambulacrals of 
the anal side, which are barely convex. Orals very large, almost symmetri- 
cally arranged ; the posterior one a little larger and wedged in between the 
others. The plates of the disk ambulacra large and tuberculous, extending 
out to the ends of the distichals and forming rigid tubular extensions. Inter- 
ambulacrals three, the middle one twice as long as the two at the sides, but 
without touching the orals. The middle plate of the anal side considerably 
