BATOCRINID &. | 409 
incurving ; pinnules closely packed. Interbrachials variable in number, 
either arched over by the higher brachials, or in contact with the inter- 
ambulacral pieces. Interdistichals frequently represented, and occasionally 
interpalmars. Anal tube stout, central and extremely long. Orals excen- 
tric ; the posterior one much larger than the others and erect, forming the 
base of the anal tube at the anterior side. Column round, with a small 
pentangular canal. 
Dnstribution.— Restricted to the Upper Burlington limestone and Keokuk 
group of America. 
Type of the genus. — Hutrochocrinus Christyi (Shumard). 
Ltemarks. — Eutrochocrinus approaches Dizygocrinus in its arm structure, 
but differs from it essentially in other respects. In Dizygocrinus the calyx 
is subglobose, the tegmen high, the arms rather long, the anal tube short 
and slender. In wtrochocrinus the calyx is decidedly wheel-shaped, the 
ventral disk almost flat, the arms very short, and the anal tube extremely 
long. 
EKutrocrinus Christyi (Suvmaxp). 
Plate X XIX. Fig. 6, and Plate XXXIT. Figs. 1a, b, c. 
1848. Actinocrinites —Curisty’s letters on Geology, Plate I., Figs. 1 and 2. 
1855. Actinocrinus Christyi—SuumMaRrp; Geol. Rep. Missouri by Swallow, Part II., p. 191, Plate Al, 
Fig. 3. 
1873. Batocrinus Christyi — Mex and WortuEn; Geol. Rep. Illinois, Vol. V., Plate 5, Figs. 4a, 6. 
1878. Batocrinus Christyi— W. and Sp.; Proceed. Acad. Nat. Sci. Phila., p. 231. i 
1885. Actinocrinus Christyi —Quunstept; Handb. der Petrefactenkunde (Auflage 3), Plate 77, Fig. 4. 
1881. Batocrinus Christyi — W. and Sp.; Revision Paleocr., Part II., p. 166. 
(not Actinocrinus Christyi — Hat, 1863 = Periechocrinus Whitfieldi). 
Syn. Batocrinus bisbrachiatus WurtrirLD ; Mem. Amer. Mus. Nat. Hist., 1893, Vol. I., p. 13, Plate 
2, Figs. 4, 5. 
Syn. Batycrinus altiusculus Mruuur and GuruEy, 1894; Geol. Surv. Missouri, Bull. 3, p. 20, Plate 5, 
Figs. 1, 2, 3. 
Calyx large, wheel-shaped; plates thick and without ornamentation. 
Dorsal cup almost twice as high as the ventral disk ; sides concave, grad- 
ually spreading to the top of the radials, and more abruptly thence to the 
arm bases; plates nearly flat. | 7 
Basal cup large, somewhat wider than high, a little thickened near the 
lower end, and projecting laterally beyond the sides of the column; the 
bottom deeply excavated. Radials quite variable in form, but generally 
longer than wide; the upper face concave. Costals small, both together not 
more than half the size of the radials; quadrangular and pentangular. Dis- 
tichals and palmars in two rows; the latter larger than any of the other 
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