538 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
as also the ambulacral plates, except near the outer margins of the tegmen, 
where well defined covering and side pieces are on a level with the interam- 
bulacrals ; and similar pieces occur along the arms. The covering plates are 
quite regular in their arrangement, forming a sort of ridge with a row of 
side pieces at each side. Anus excentric, at the top of a short, rounded or if 
| conical protuberance. Column large, giving off heavy branches at the distal 
| end; it increases but little in width, and is composed throughout of alter- 
| nate thick and thin joints, Central canal moderately large, obscurely penta- 
lobate, and proportionally wider at the lower end. 
i | Horizon and Locality. — Kinderhook group; Le Grand, Marshall Co., 
1 Towa. . | 
collection of Wachsmuth and Springer. 
fiemarks. — Megistocrinus parvus has the same affinities with JZ. nobilis as 
“ Actinocrinus”’ brevicornis with Megistocrinus Evansi, and we regard it a 
HiT young stage of that species. The arms are free above the distichals, and 
|| it has less interbrachial plates. The specimen, Plate LI., Fig. 8, is some- 
) 
“| Type at Pasadena, California, but authentic specimens are in the 
| what abnormal, having but one costal in two of its rays. 
Megistocrinus latus (Hatt). 
Plate XL VILLI. Figs. dd, 0. | 9 
1858. Hatz; Geol. Rep. Iowa, Vol. I., Part ieee 480, Plate 1, Figs. ae 
1881. W. and Sp.; Revision Paleocr., Part IL., p. 138. 
A large species. Dorsal cup short, about twice as wide as high, abruptly 
depressed at the bottom; the sides expanding upwards; arm bases slightly 
projecting; plates flat and without ornamentation; suture lines grooved. | 
Rete ee | 
— = — 
Basals closely anchylosed, rather large, located at the bottom of an 
inverted cup, which is a little wider than the column. Radials about as 
wide as long; their lower ends abruptly curved to form the sides of the 
x 
~ole 
| 
basal concavity, the other portions spreading horizontally and constituting | 
the bottom of the calyx. First costals generally longer than the second. | 
Distichals in the antero-lateral rays three, supporting two arms; the other | 
rays have a single axillary, followed by several palmars with four arms to the | 
1 | | ray. Interbrachials: 1, 2, 8, 3, and some small pieces between the arm 
H)) bases. The first anal plate, which is a little narrower than the radials, is suc- 
ceeded by three plates, and these by numerous irregularly arranged pieces, | 
