MELOCRINID®. 315 
lary distichal followed by 3 X 2 palmars and two arms, upon the other three 
fixed distichals, which support one arm, There are three primary arms, two 
and one, to the ray; two of the simple arms facing the anal interradius. 
Arm openings directed obliquely upwards, less projecting and smaller than 
usual in the genus. Interbrachials: 1, 1, 3, 4; the first large, rather angular 
below, broadly truncate above, the upper sides a little wider than the lower ; 
the second almost as large as the first, with a long transverse node. The 
three plates of the third row much smaller and provided with elongate nodes. 
The plates of the fourth row, which occupy the arm regions, are small and 
highly convex, their upper faces pierced by the lower part of the slits. The 
interambulacral plates consist of five large cuneate plates, of which the three 
middie ones are larger than the others; the sides of the outer ones excavated 
to form the slits, which are quite large in this species. The anal interradius 
has a few additional plates in the disk, which connect with the anal tube. 
Interdistichals four to the arm regions, arranged in two rows, followed by 
three cuneate interambulacral plates, with two slits, while there are four slits 
above the interbrachial spaces. Orals large, all of similar form and size, 
surrounded by good sized radial dome plates of a first, second, and third 
order. Anal tube almost central, its base formed of rather large convex 
plates. 
Horizon and Locality. — Upper Helderberg group; Clark Co., Ind. 
Types in the collection of Victor W. Lyon, Jeffersonville, Ind. 
Remarks. —This species is readily distinguished from all others of this 
genus known to us by the grotesque style of its ornamentation. 
Dolatocrinus canadensis WHITEAVES. 
Plate XXV. Figs. 7a, b. 
1887. Wurreaves; Geol. and Nat. Hist. Surv. Canada; Contrib. to Can. Paleont., Vol. I., p. 99, Plate 12, 
figs. 3, 3a. 
Of the type of Dolatocrinus Marshi, but with a different arm formula. 
Calyx small, much wider than high. Dorsal cup broadly and shallowly 
basin-shaped, slightly depressed along the radials, and more conspicuously at 
the basals. Ventral disk lower than the dorsal cup; hemispherical ; the 
central portions slightly tumid. The ornamentation of the dorsal cup con- 
sists of numerous parallel ridges, passing out to. the sides of the plates, and 
meeting those of adjoining ones. The rays along their median lines followed 
