A Sn 
hres: 
732 THE CRINOIDEA CAMERATA OF NORTH AMERICA 
its fellow of the same ray, the opposite side against the large interradial 
plate, the lower face resting upon the radials. The second distichal trigonal, 
very small, not larger than the costals, the two of the same ray together 
forming a triangle, from the sloping sides of which the arms are given off, the 
lower arm plates resting partly upon the distichals. Arms two to the ray, 3 
divergent, rapidly tapering at the base, and rather slender above; they are 
biserial from their origin, and the proximal row of arm plates takes part in 
the calyx. First plate of the interradial series very large, its lower portion 
SS y= 
- 
constituting a part of the dorsal cup, the upper part entering into the 
ventral disk; it bends abruptly inward at two thirds its height, forming | 
a sharp edge along the margin. The lower end of the plate deeply wedged 
in between the radials, the middle portion resting against the sides of the 
ES ee: 
Sawa 
== — 
distichals, the inflected upper end against the covering plates of the ambu- 
; lacra. This plate at the four regular sides is followed by two rows of inter- 
== 
yall ambulacral plates, generally arranged three and two, of which the upper 
‘eal row abuts against the orals. The anal side has from ten to twelve plates 
a | of irregular arrangement. Ventral disk depressed hemispheric, the plates 
tt | tumid, with a small tubercle in the middle. Orals excentric and asymmetrical, 
the posterior one wider than long, but not larger than the others. Ambu- 
aa | Jacral plates much smaller than the surrounding plates; the primary ambu- 
| Jacra roofed by three series of plates, the two outer ones consisting of short, 
transverse pieces, separated by a few elongate plates. The covering pieces 
| 
| of the secondary ambulacra much smaller, and separated by one or two 
| large interaxillary pieces; they are composed of two rows of regularly alter- 
WA) | nating plates. Anus almost central. Column round, so far as observed; 
the axial canal pentagonal. 
Horizon and Locality. — Niagara group; Decatur and Wayne Cos., Tenn. 
Lypes in the Mineralogical Museum at Breslau, Germany. 
1 Weed Marsupiocrinus striatus W. and Sp. (nov. spec.). 
ays Plate LXXV. Figs. 17, 18. 
A little larger than the preceding species, sometimes attaining a width of 
6cm. Calyx twice as wide as hich, height of the dorsal cup about equal to 
that of the disk. Dorsal cup truncated to near the middle of the radials, 
then abruptly spreading upwards, the upper end slightly curving inward. 
Plates densely covered by fine stria passing from the radial facets out to the 
