BATOCRINID&. | 527 
two plates each. Interdistichals, 1, 2, 2; the first resting within the notch of 
the first distichals. Anal side remarkably wide. The anal plate, which closely | 
resembles the radials, followed by three rather large plates, and these by | 
three smaller ones and an elongate plate at each side, which latter rise to | 
the top of the plates of the third row, so that the second and third rows to- | 
gether contain eight plates. This arrangement, however, is not invariable; | 
there are some specimens in which these rows have five plates each, and the 
plates above, on approaching the tegmen, form a rounded, conspicuous ridge, 
which connects with the anus. The course of the ambulacra is indicated in 
the casts by well marked ridges, which branch twice upon the surface, 
and show that there was a third bifurcation in the calyx. Ventral disk 
hemispherical, composed of rather uniform pieces of moderate size. Anus 
subcentral. 
Horizon and Locality. — Upper part of Niagara group; Chicago, Ills. | 
Remarks. —We have carefully compared Miuller’s types of his “Sacco- | 
crinus” pyriformis with the types of Periechocrinus urniformis, both in the 
collection of Mr. Egan of Chicago, and came to the conclusion that the dif- 
ferences pointed out in the descriptions are not constant, and are to a large 
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extent imaginary. | 
: 
(?) Periechocrinus ornatus (H4tr1z). | 
) 
Plate L. Figs. 8a, 6, and Plate LI. Fig. 7. 
1875. Saccocrinus ornatus — Hatt; Geol. Rep. Ohio, Palont., Vol. II., p. 126, Plate 6, Figs. 7 to 9. 
1881. Periechocrinus ornatus — W. and Sp.; Revision Paleocr., Part IL., p. 132. 
Syn. Saccocrinus Benedicti —S. A. M1ntER; 1892, Adv. Sheets 18th Rep. Geol. Surv. Indiana, p. 29, 
Plate 5, Figs. 1 and 2. 7 
A smaller species than the preceding one. Calyx obovate; the dorsal cup 
elongate urn-shaped, obscurely pentangular in the upper portions, the rays | 
at the arm bases widely separated, especially upon the posterior side. Plates 
highly elevated, subconical, with deeply channeled sutures; the surface coy- 
ered with coarse rugosities or irregular protuberances, meeting in the centre 
of the plates, and passing out to the edges. 
Basals rather large, forming a moderately spreading cup. Radials and 
Se 
costals higher than wide, gradually decreasing in size; the former consid- 
erably larger than the costals. Distichals free from above the third plate. 
Arm structure unknown. Interbrachials in five rows; the first plate as large 
as the first costal; there are two in the second range, and five in the three 
