410 THE CEINOIDEA CAMERATA OF NORTH AMERICA. 



brachials. The upi^er row of pahnars deeply excavated for the reception of 

 the free arras, and the facet occupied by a diminutive axillary, and two small 

 arm plate.s, 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 palinars, 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- 

 jDort 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 iipper 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 

 Missouri. 



EemarJis. — Mdrochoerinus Cristyi is very closely allied to E. 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. trochiseus (Meek and Woethen). 

 FMe XXXII. Fig. 3. 



1868. Bafocrinus iroehisens — Meek and Wokthen ; Proceed. Acad. Nat. Sci. PMa., p. 354. 

 ' 1873. Batocrinus trochiseus — Meek and Woethen; Geol. Rep. Illinois, Vol. V., p. 372, Plate 5, Pig. 6. 

 1S78. Var. of Batocr. ChrisUji — 'W. and Sr.; Proceed. Acad. Nat. Sci. Pliila., p. 231, and 1881, Kevision 

 Palaiocr., Part II., p. 168. 



Larger, and throughout more extravagantly developed than the typical 

 form. Calyx more spreading and comparatively shorter, narrower at the 



