410 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
brachials. The upper row of palmars deeply excavated for the reception of 
the free arms, and the facet occupied by a diminutive axillary, and two small 
arm plates, which support an arm each. There are twenty arm openings, 
arranged at nearly equal distances, and directed horizontally. Arms forty, 
two to each opening; they are short, infolding, comparatively thin, and 
composed from their bases up of two rows of short transverse pieces. Pin- 
nules flattened at their sides and contiguous. Interbrachials three to five in 
three rows, the lower one large, about as wide as high, the others small and 
arched over by the palmars, which meet laterally, forming a continuous ring. - 
Anal plate elongate, followed by three, three and two plates. Ventral disk 
depressed near the periphery, the median portions gradually rising to sup- 
port the anal tube. Plates convex; the orals and radial dome plates 
considerably larger than the interambulacral pieces. The orals placed ante- 
riorly ; the posterior one twice the size of the other four, directed upwards, 
and forming at the anterior side the base of the anal tube. Anal tube 
extremely long, sometimes arising to a height of four inches; thick at the 
base, but gradually tapering until it is quite slender at the upper end. 
Column of moderate size, round; the nodal joints rather high, cylindrical ; 
the internodal ones increasing to four at three inches from the calyx. 
Horizon and Locality. — A characteristic fossil of the Upper Burling- 
ton limestone; Burlington, Iowa, and several other places in Illinois and 
Missoura. 
Remarks. — Eutrochocrinus Cristyt is very closely allied to HZ. Lovei, and 
unless the arms are preserved or the arm openings very perfect, it is 
difficult to separate them. ‘That the two are evolved from a common 
type is well shown by the fact that in young specimens of E. Christyi 
one or two arms are frequently simple; while the larger ones invariably 
have two arms to each arm opening. 
Eutrochocrinus Christyi, var. trochiscus (Mzex and Worruey), 
Plate XX XIT, Fig. 8. 
1868. Batocrinus trochiscus— Mzrx and WortHEn ; Proceed. Acad. Nat. Sci. Phila., p. 354. 
1873. Batocrinus trochiscus —Mxrxrx and WortHEn; Geol. Rep. Illinois, Vol. V., p. 872, Plate 5, Fig. 6. 
1878. War. of Batocr. Christyi — W. and Sp.; Proceed. Acad. Nat. Sci. Phila., p. 231, and 1881, Revision 
Palecocr., Part Ll,p. 168; 
Larger, and throughout more extravagantly developed than the typical 
form. Calyx more spreading and comparatively shorter, narrower at the 
‘a ——— 
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