BATOCRINiDiE. 547 



area, and in the form and position of the anus, in all of which it resembles 

 Aorocrinus. Lyon's tyjje is in an abnormal condition, and we have figured 

 other specimens in place of it. It has but four arm-bearing rays, the postero- 

 lateral ray apparently having been injured during the life of the Ci'inoid, 

 and the space from the first axillary up being filled by abnormal growth. 

 Besides the left antero-lateral ray has four in place of two primary arms. 

 Whether the arms of this species are branching is not known. 



GENN^OCRINUS W. and Sp. 



1881. W. and Sp.; Revision Palaeocr., Part II., p. 160 (Proceed. Acad. Nat. Sci. Pliila., p. 334). 

 1891. S. A. MiiLEK; Nortli Amer. Geol. and.Palaiont, , p. 247. 

 S^a. Actinocrintis (m^ail). 



Calyx distinctly lobed ; the interradial spaces extremely wide, and deeply 

 indented at the arm regions. Plates thin, their surfaces ornamented with 

 radiating strife. Basals three, small ; the axial canal large and pentalobate. 

 Eadials and costals of similar form, but decreasing in size upwards ; the first 

 costal hexagonal, the second heptagonal. The branching of the rays above 

 the distichals is from alternate sides, the second plate of the two main divi- 

 sions giving off at one side an arm, at the other brachials of a higher order, 

 the last axillary supporting two arms. The different rays have the same 

 number of arms, which is eight, so far as observed. Interbrachials quite 

 numerous, and the upper ones in contact with the interambulacrals; the first 

 is followed by two or three in the second row — which are larger than usual 

 in the BatocrinidiB — and these by three or four smaller ones. The first 

 anal plate supports a second, which has an intei'brachial at each side, and 

 there are several rows of four or more plates above. The tegmen is com- 

 posed of rather small plates, and rises but little above the dorsal cup ; the 

 surface is undulated, being grooved and indented interradially, and distinctly 

 raised all along the food grooves, which are covered by two rows of alternate 

 pieces. Orals proportionally small, the posterior one a little the largest. 

 There is no anal tube, the anus being represented by a small, excentric 

 opening, passing out directly through the tegmen. 



Distribution. — Eestricted to the Hamilton group of America. 



Type of the genus. — Gennwocrinus Tcentuchiensis (Shumard). 



RemarJcs. — This genus, in the branching of the rays, grouping of the 

 arras, form of the tegmen, and in the simplicity and position of the anus. 



