340 PROCEEDINGS OF THE ACADEMY OF [1879. 



on each side an arm which remains simple throughout; the an- 

 terior ray sometimes has but one arm. Arms long, composed of 

 quadrangular or slightly cuneiform joints ; pinnulse of moderate 

 size. Column round or obtusely pentagonal. 



a. Species with a Single Brachial. 



*1875. Poteriocrinus (Scytalocrinus) abnormis Worthen. (Scaphiocr. abnormis.) 



Geol. Rep. 111., vol. vi. p. 519, pi. 31, fig. 6. St. Louis limest- Subcarb. 



Monroe Co., 111. 

 1873. Pot. (Scytalocr.) Bisselli Worthen. Geol. Rep. 111., vol. v. p. 546, pi. 21, 



fig. 4. Chester limest. Subcarb. Chester, 111. 

 1843. Pot. (Scytalocr.) dactyloides Austin. Ann. and Mag. Nat. Hist., vol. x., 



p. 108; vol. xi. p. 197; Rec. and Foss. Crin., p. 86, pi. 10, fig. 7, and pi. 



11, figs. 1 a, b. Subcarb. Ireland. 

 *1860. Pot. (Scytalocr.) dactylus Hall. (Graphiocr. dactylus.) Supp. Geol. 



Rep. Iowa, p. 80. St. Louis limest. Subcarb. Missouri and Illinois. 

 I860. Pot. (Scytalocr.) decadactylus Meek & Worthen. (Not Cyathocrinus. 



= Poteriocr. decadactylus Lyon & Cass. = Scaphiocr. Coreyi Worthen. 



= Pot. (Scytalocr.) grandis Wachsm. & Spr ) Trans. Acad. Nat. Sci. Phil., 



p. 394; Geol. Rep. 111., vol. ii. p. 338, pi. 17, fig. 6. Keokuk limest. Sub- 

 carb. Illinois. 

 1858. Pot. (Scytalocr.) decabrachiatus Hall. Geol. Rep. Iowa, vol. i. pi. 2, p. 



679, p. 25, fig. 1. Chester limest. Subcarb. Kaskaskia, 111. 

 Syn. Scaphiocr. longidactyhis McChesney, Dec. 1S59, New Pal. Foss., p. 7; 



Trans. Chicago Acad. Sci., 1867, vol. i. pt. i. p. 4, pi. 4, fig. 4. 

 1865. Pot. (Scytalocr.) Indianensis Meek & Worthen. Proc. Acad. Nat. Sci. 



Phil., p. 155; Geol. Rep. 111., vol. iii. p. 515, pi. 20, fig. 4. Keokuk 



limest. Subcarb. Crawfordsville, Ind. 



This species, if not based upon an abnormal specimen of P. ro- 

 bustus Hall, differs from all the others in this section in having 

 two brachials, and in having an additional arm in the posterior 

 rays. 



*1869. Pot. (Scytalocr.) macrodactylus Meek & Worthen. (Scaphiocr. macro- 

 dactylus.) Proc. Acad. Nat. Sci Phil., p. 140; Geol. Rep. 111., vol. v. 

 p. 415, pi. 2, fig. 9. Upper and Lower Burl, limest. Subcarb. Burlington, 

 Iowa. 



*1858. Pot. (Scytalocr.) maniformis Hall. (Zeacrinus maniformis.) Geol. Rep. 

 Iowa, vol. i. pt. ii. p. 682, pi 25, fig. 8. Chester limest. Subcarb. Illi- 

 nois. Kentucky and Tennessee. 



This species shades into several genera, and cannot be satis- 

 factorily brought under any of them. It agrees with Graphiocri- 

 nus, except in the anal area; the arm joints are like those of 

 Zeacrinus, but the arms are simple instead of bifurcating ; it 

 agrees with Eupachycrinus in the form of the calyx and in the 

 anal area. 



