162 PROCEEDINGS OF THE ACADEMY OF [1886. 



bent upward and forming a conspicuons part of the calyx. Radials 

 and brachials of nearly the same form, apposed faces truncate, with 

 a transverse articular ridge and somewhat shallow fossae ; line of 

 articulation gaping. The brachials either single or compound, 

 generally elongate, constricted along the middle. They support 

 two simple arms each, except in the anterior ray, which some- 

 times has but a single arm. Arms long, rather heavy, composed 

 of quadrangular or slightl}^ cuneiform joints ; pinnules of mode- 

 rate size. Azygous side as in Poteriocrinus ; ventral sac tubular, 

 with slit-like openings, and frequently spiniferous at the distal end. 

 Column circular or obtusely pentagonal. 

 Additional species : 



a. With single brachials. 



*1877. Scytalocrinus loreus (Sladen), Dactylocrinus loreus (Poteriocrinus tenuis 

 Austin, non Miller), Mon. Rec. and Foss. Crin., PL 10, fig. 5. On the genus 

 Poteriocrinus, etc., p. 5. Subcarboniferous. England. 



*1821. S. tenuis Miller, Nat. Hist. Criu., p. 71, PI. 21-23. Dactylocrinus tenuis 

 Sladen, 1877, "On the genus Poteriocrinus, p. 5." 



*1880. S, Wachsmuthi Wetherby, Journ. Cincin. Soe. Nat. Hist. (July), p. 12, PI. 5, 

 fig. 4. Kaskaskia limest. Pulaski Co., Ky. 



b. With compound brachials. 



(Poteriocrinus hamiltonensis Worthen, 1882, Bull, i. 111. St. Mus. Nat. Hist., 

 p. 7; Geol. Rep. Illinois, vii, p. 273, PI. 28, fig. 9, Syn. of Poteriocr. 

 (Scytalocr.) robustus Hall). 

 *1882. Scytalocrinus Talboti (Worthen), Poteriocrinus Talboti, Bull, i. 111. St. Mus. 

 Nat. Hist., p. 17; also Geol. Rep. Illinois, vii, p. 287, PI. 30, fig. 7. St. 

 Louis limest. Monroe Co., 111. 



DECADOCRINUS W. and Sp., Rev. I. p. 119. 



Arms ten, rarely nine, the anterior ray sometimes undivided. 

 Dorsal cup depressed, saucer-shaped, with a deep concavity along 

 the basal regions. TJnderbasals small, not seen in a side view, 

 and frequently covered almost entirely by the column. Form of 

 radials and brachials and articulation as in Scytalocrinus ; brachi- 

 als simple or compound. Arms composed of single wedge-form 

 joints, with keel-like projections at alternate sides, and with 

 strongly waving or zigzag outlines. Pinnules unusually strong, 

 placed far apart, and resembling armlets ; composed of short 

 cuneate joints, with spurs or keels upon theirbasal joints. Azygous 

 side as in Poteriocrinus. Yentral sac more or less club-shaped ; 

 constructed of numerous rows of regularly arranged hexagonal 



