BATOCRINID.&. | 543 
the first costals and first interbrachials, then curving abruptly upward, widen- 
ing a little in the upper part. Surface of plates, except basals and radials, 
strongly nodose, the nodes cut up by irregular grooves or coarse wrinkles, 
which give to the species an extremely rugged appearance. 
~ Basals small, flat, disk-like, slightly depressed, only the points of the 
angles projecting beyond the column; central perforation large and pentalo- 
bate. Radials, first costals, and first anal plate hexagonal and of nearly 
the same size; the second costals pentagonal, hexagonal, or heptagonal, 
owing to the height of the interbrachials of the second row. Distichals 3 x 2 
in the antero-lateral rays, decreasing in size; the lower one almost as large 
as the preceding axillary. The three other rays have but one distichal, and 
2 or 3 X 4 fixed palmars, of which the upper one is short and curved like an 
arm plate. Arm openings sixteen, arranged in groups of two and four; the 
arm structure not known. Interbrachials: 1, 2,3, 38,3. Anal plate followed 
by rows of 4, 5, and 4 plates, and a few irregular pieces at the arm regions. 
Ventral disk depressed-subconical; composed of numerous convex pieces ; 
the orals and radial dome plates large and spinous, and all isolated. Anal 
tube excentric, strong at the base; consisting of slightly elevated pieces with 
spine-bearing larger ones interspersed. Column unknown. 
Horizon and Locahiy.— Hamilton group (Corniferous), Clark Co., Ind., and 
Louisville, Ky. 
Megistocrinus concavus WAcusMmurTuH. 
Plate XL VIL. Figs. 5a, b, c. 
1885. WacusmutH ; Proceed. Davenp. Acad. Nat. Sci., Vol. IV., p. 96, Plate 1, Figs. 5, 6, 7. 
1885. W. and Sp.; Revision Paleocr., Part III., p. 112. 
A rather aberrant form of the genus. Calyx wider than high, the ventral 
disk higher than the dorsal cup; the latter very shallow, abruptly depressed 
to the top of the radials; the first costals spreading horizontally, and form- 
ing a wide and deep inverted cup; the second bending abruptly upward so 
as to place the upper part of the calyx almost at right angles to the trun- 
cated lower part. Plates heavy, and except the basals, radials and first anal 
plate, which are flat or a little concave, produced into broad, very prominent 
knobs. 
Basals of medium size, forming a hexagonal disk, which occupies the 
bottom of the concavity. Radials comparatively small, slightly bending 
upwards, and constituting together with the lower margins of the first costals 
