040 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Megistocrinus depressus (Hatt). 
Plate XLIX. Figs. 2, 3, and La-d. 
1862. Hann; 15th Rep. N. Y. State Cab. Nat. Hist., p. 134. 
1881. W. and Sp.; Revision Paleocer., Part II., p. 187. 
Syn. Megistocrinus ontario Haut, 1862; loth Rep. N. Y. State Cab., p. 136. 
As large as the preceding species. Calyx depressed, wider than high ; 
the dorsal cup basin-shaped ; the bottom part to the middle of the first cos- 
tals — sometimes higher — flattened but not excavated; the sides slightly 
expanding to the top of the distichals, thence curving outward and forming 
a short rim, from which the free arms are given off in pairs. Plates flat or a 
little concave, thickened around their outer margins, and in well preserved 
specimens covered by numerous very fine, somewhat irregular strix, which 
are more pronounced near the suture lines; the middle of the plates 
sometimes slightly elevated, and the surface covered with small irregular 
pustules. 
Basals small, only the points of the outer angles visible beyond the 
column; almost flat, and on a level with the radials; the axial canal large 
and indistinctly pentagonal. Distichals from one to three in the calyx. 
Three of the rays have a single distichal in both divisions, which is axillary 
and followed by 2 x 2 short palmars, the other rays two additional distichals 
and no palmars. Arm openings sixteen, arranged in eight pairs. The median 
lines of the higher brachials are ornamented with indistinct, longitudinal 
ridges, covered by similar strize as the other parts of the plates. Inter- 
brachials: 1, 2, 3, with two or three irregular rows above, which meet the 
interambulacral plates. First anal plate, which is a little larger than the 
radials, followed by 3, 4, and 4 pieces, and these by a number of smaller 
ones. Interdistichals one to three, arranged longitudinally; the rays with four 
arms generally having three, the others not more than two. Ventral disk 
depressed-convex ; the food grooves marked by ridges, which diverge to the 
arm bases; the surface is covered by rather large, flat, irregular pieces 
enclosing the orals and radial dome plates, which are but little larger than 
the rest of the plates. Posterior oral in contact with the others, central and 
spiniferous, while the other four are generally flat. Anus excentric. 
Horizon and Locality. — Hamilton group; Western New York and 
Louisville, Ky. 
Lp — 
