PLATE \l 
Fig. 1. Agelacriniis auslini, Foerste. A, specimen showing peripheral ring, 
with outer zone of small marginal plates, and inner band of larger plates. The 
anal pyramid is on the right, a short distance above the horizontal diameter. 
Ray 5 is directed upward and toward the right. Ray 4 is turned toward the left. 
The terminal part of ray 3 is well preserved. The long median or central cov- 
ering plates are well shown in the specimen but can not be distinguished in the 
figure. B, lower side of upper part of the theca, showing the substornial chamber. 
The anterior outline, formed by the modified proximal floor plates of rays 2, 3 and 
4, is well preserved. The outer ends of the proximal floor plates of rays 1 and 5 
are in position, but the inner ends, toward the median line of the specimen, have 
been swung forward, partly closing the substornial ravity, evidently owing to 
displacement after death. The floor plates of rays 2 and 3, and a part of those of 
ray 1, are well preserved. They consist of a single series in the case of each ray, 
and no glimpse of the basal extensions of the lateral covering plates may be seen. 
C, one of three specimens resting upon the flattened surface of a bryozoan which 
had been very much worn before the attachment of the specimens. Anal area 
on the left. The curvature of the rays is less than in fig. lo. Interambulacral 
plates more numerous in the distal part of the posterior area than in any of the 
other interambulacral areas. All figures magnified 4.2 diameters. Specimens 
in the collection of Dr. G. M. Austin; from the Drepanella richardsoni horizon, 
at the toji of the Whitewater member of the Richmond, on Dutch creek, south 
of the Oakland ])ike, four and a half miles northwest of Wilmington, Ohio. 
Fig. 2. Lepidodiscus alleganius, Clarke. A, oral aspect of a mature indi- 
vidual, showing the extremely narrow, undulating, whiplash rays, all solar: 
the small cover plates; the anal pyramid composed of 10 triangular plates: and the 
absence of specially differentiated marginal plates. Magnified 1.5 diameters. 
Chemung sandstone. Loose at Alfred, New York. B, Aboral aspect of a large 
individual, showing the depressed surface with imbricating plates directed cen- 
trifugally and the projecting margin of coarser plates. Natural size. Chemung 
sandstone. Loose at Belvidere, New York. Figures copied from Bull. 49, N. 
Y. State Museum, 1901, pi. 10, figs. 4, 2. Plastotypes Nos. 4285-4 and 2 re- 
spectively, in the New York State Museum, at Albany, N. Y. 
Fig. 3. Agelacriiiites hamiltonensis, Vanuxem. Drawing made from gutta- 
percha replica of original, showing form and direction of rays, the large submar- 
ginal and small marginal plates, the sculptured surface of the interambulacral 
plates, and the anal pyramid. Magnified 2 diameters. Hamilton beds. West 
Hamilton, Madison county. New York. Part of figure 6, on pi. 10 of Bull. 49, 
X. Y. State Museum, 1901. Plastotype No. 4000-1, New York State Museum. 
Fig. 4. Streptaster vorticellatus, Hall. A portion of the peripheral ring of 
the type, showing the relative size and arrangement of the plates. Magnified 5 
diameters. Ma 3 ^sville formation, Cincinnati, Ohio. Type, No. 1192, in the 
American Museum of Natural History, in New York City. Copy of fig. 12 on 
pi. 6, of the 24th- Annual Report of the N. Y. State Museum, 1872. 
Fig. 5. Cystaster granulatus. Hall. A, view of the summit of a specimen, 
enlarged 4 diameters, showing the covering plates of the rays and the anal pyra- 
mid. B, lateral view of a specimen, with the covering plates of the rays missing; 
only lower range of plates of anal p\umnid present, lower margin shows cicatrix 
of attachment to some foreign body. C, oblique summit view of another indi- 
vidual, with covering plates present onh" on the two nearer ra^^s. B and C, en- 
larged 2.5 diameters. D, lateral view of a specimen with a more elongate bod}", 
pointed below, showing no evidence of having been attached; covering plates 
absent. Enlarged 3 diameters. The originals of figures B, C, and D are numbered 
40 in the Dyer collection, at Harvard ITniversity. The original of fig. A should be 
in the same collection but was not noticed by me. Fairmount member of the 
Maysville formation, at Cincinnati, Ohio. Copied from figs. 1, 2, 3, 4, on pi. 
6, in the 24th Ann. Rept. N. Y. State Museum. 
Fig. 6. Hemicystites stellatus, Hall. A, a small individual, enlarged 6 
diameters. Rays with covering plates, about 7 or 8 in each range. With distinct 
imbricating plates and anal pyramid. On Rafinesquina alternata. Type, No. 
1191-1, in the American Museum of Natural History, in New York City. B, a 
summit view of a larger individual, enlarged 4 diameters. Covering plates miss- 
ing. Interambulacral plates in the upper left-hand area, distinctly inibricating. 
Maysville formation. No. 1193 in Dyer collection at Harvard LTniversity. 
486 
