BATOCRrNID^. 387 



second pentangular, their sloping upper faces placed at right angles. Dis- 

 tichals two, the axillary considerably wider. Palmars three, shorter than the 

 distichals, in contact laterally, and so arranged that the salient angle of one 

 plate rests within the retreating angle formed by the two adjoining joieces. 

 Arm openings dkected horizontally, arranged in groups, the interspaces 

 between the rays being wider than the others. Arms twenty, exceptionally 

 twenty-two, when there are five in the two posterior rays. According to 

 Tijon and Casseday, the arms are four inches long, subcylindrical to one 

 third their length, when they flatten and expand upwards, reaching at 

 midway a width of half an inch, and a depth of one sixteenth, but higher 

 up their width is reduced to one half, and they end in a rounded edge. 

 The arms are biserial above the first or second free plate. The plates are 

 short near the calyx, but increase in length upward. Interradials two to 

 three ; the first rising to one half the height of the first distichals. The 

 anal interradius has six plates above the anal, arranged in two rows. 

 Ventral disk high-conical, surmoimted by a small, almost central anal tube ; 

 the plates large and tumid. 



Horizon and Locality. — Keokuk group; Clear Creek, Hardin Co., Ky. ; 

 New Eoss, Montgomery Co., Ind. ; Pilot Knob, near Louisville, Ky. ; and 

 White's Creek Springs, near Nashville, Tenn. 



Type in the collection of the late S. A. Casseday. 



Eretmocrinus ramulosus (Hall). 

 Plate XXXVII., Figs. 4^, b, and 5 a, h, c, d. 



1858. Actmocritms ranmloms — Hall; Geol. Eep. Towa, "Vol. I., Pirt II., p. 615, Plate 15, Fig. 7. 

 1881. Eretmocrinus ramulosus — W. and Sp. ; Rcvisiou Palseocr., Part II., p. 173. 



Not Eretmocrinus ramulosus W. and Sp. ; 1873, Proceed. Acad. Nat. Sci. Phila., p. 23&:= Eretmocrinus 

 remibrachiutus, var. expansus. 



The largest species of this genus. In its general aspect closely resem- 

 bling E. marjnificus, but more rugose; the ridges and nodes more prominent; 

 the base narrower ; the ventral disk larger, and hemispherical instead of 

 conical ; the anal tube much smaller, being reduced to the minimum. 

 Dorsal cup short, rapidly spreading, truncate at the base. Plates elevated 

 and covered with sharp central tubercles ; those upon the radials and 

 brachials confluent, forming undulating angular ridges, which branch upon 

 the axillaries and pass into the arms, producing deep depressions between 

 the various divisions of the rays. The radials and brachials have two addi- 



