1879.] NATURAL SCIENCES OF PHILADELPHIA. 339 



short and infolding arms and in the concavity of its basal portions; 

 but it differs from both in the construction of the ventral sac, 

 which in this group is almost cylindrical, with a tendency toward 

 a balloon shape. 



*1873. Poteriocrinus (Pachylocrinus) arboreus Worthen (Zeacrinus arboreus). 

 Geol. Rep. 111., vol. v. p. 534, pi. 20, fig. 5. St. Louis limest. Subcarb. 

 Huntsville, Ala. 



*1869. Pot. (Pachylocr.) asper Meek & Worthen. (Zeacr. asper). Proc. Acad. 

 Nat. Sci. Phil., p. 150 ; Geol. Rep. 111., vol. v. p. 430, pi. 1, fig. 7. Burl, 

 limest. Subcarb. Burlington, Iowa. 



1870. Pot. (Pachylocr.) concinnus Meek & Worthen. (Pot. (Zeacr.) concinnus.) 

 Proc. Acad. Nat. Sci. Phil., p. 26; Geol. Rep. 111., vol. v. p. 490, pi. 14, 

 fig. 3. Keokuk limest. Subcarb. Crawfordsville, Ind. 



1843. (?) Pot. (Pachylocr.) latifrons Austin. Rec. and Foss. Crin., p. 82, pi. 10, 

 fig. 4. Subcarb. England (closely resembling Zeacrinus). 



1869. Pot. (Pachylocr.) liliiformis Meek & Worthen. Described June, 1861, un- 

 der Pot. carinatus M. & W. (not Scaphiocr. carinatus Hull, February, 

 1861), Proc. Acad. Nat. Sci. Phil., p. 139; Scaphiocr. carinatus M. & W., 



1868, Geol. Rep. 111., vol. iii. p 486, pi. 17, fig. 1; Scaphiocr. liliiformis, 



1869, Proc. Acad. Nat. Sci. Phil., p. 138. Upper Burl, limest. Subcarb. 

 Burlington, Iowa. 



*1864. Pot. (Pachylocr.) merope Hall. (Zeacr. merope.) 17th Rep. N. Y. St. 



Cab., p. 60; Geol. Rep. Ohio, Pal , vol. ii. p. 178, pi. 12, fig. 18. Waverly 



Gr. Subcarb. Richfield, Ohio. 

 *1864. Pot. (Pachylocr.) paternus Hall. (Zeacr. paternus.) 17th Rep. N. T. 



St. Cab., p. 59 ; Geol. Rep. Ohio, Pal., vol. ii. p. 177, pi. 12, fig. 17. Waverly 



Gr. Subcarb. Richfield, Ohio. 

 *1862. Pot. (Pachylocr.) perangulatus White. (Zeacr. perangulatus.) Proc. 



Bost. Soc. Nat. Hist., vol. ix. p. 11. Upper Burl, limest. Subcarb. Bur- 

 lington, Iowa. 

 *1860. Pot. (Pachylocr.) planobrachiatus Meek & Worthen. (Zeacr. planobra- 



chiatus.) Proc. Acad. Nat. Sci. Phil., p. 391; Geol. Rep. 111., vol. ii. p. 



240, pi. 18, fig. 5. Keokuk limest. Subcarb. Monroe Co., 111. 

 *1879. Pot. (Pachylocr.) subaequalis Wachsm. & Springer Type of the group. 

 Described by Hall, 1861, as Scaphiocr. aqualis (not Pot. (Scaphiocr.) aqualis 



Hall, 1859). Desc. New'Pal. Crin., p. 8 ; Bost. Jour. Nat. Hist., p. 316 ; 



Meek & Worthen, 1873, Geol. Rep. 111., vol. v. pi. 15, fig. 6. Keokuk limest. 



Subcarb. Crawfordsville, Ind. 



E. SCYTALOCRINUS W. <!k Spr. 

 (eKvraXy a staff or club ; xpivov a lily.) 



General form of body, including arms, very slender and almost 

 cylindrical. Calyx obconical or bell shaped. Underbasals well 

 developed and bent upward; radials and brachials of nearly the 

 same form, with straight hinge line occupying the entire width of 

 the plates; brachials either single or compound, and supporting 



