1886.] NATURAL SCIENCES OP PHILADELPHIA. 93 



Column long, cylindrical ; with small central canal. 



Geological Position, etc. Symbathocrinus, commenced in the 

 Hamilton group, attained its greatest abundance in the two Bur- 

 lington formations, and disappeared at the termination of the 

 Keokuk period. 



1869. Symbathocrinus brevis Meek & Worthcn, Proceed. Acad. Nat. Sci. Phila., p. 



68; also Geol. Rep. Illinois, vol. v, p. 439, PL ii, fig. 6. Lower Burlington 



limestone, Burlington, Iowa. 

 1836. S. conicus Phillips, Geol. Yorkshire, p. 206, PI. 4, figs. 12, 13; Austin, Ann. and 



Mag. Nat. Hist., x, p. 108; also Monog. Rec. and Foss. Grin., p. 93, PI. 11, 



figs. 5 &, c (not 5 a, which is a Poteriocrinoid); d'Orbigny, 1850, Prodr. i, p. 



156; McCoy, 1854, Syn. Brit. Palaeoz. Foss., p. 118. Mountain limest., 



Ireland and England. 

 1852. S. dentatus Owen & Shuin., Jour. Acad. Nat. Sci. Phila. (new sen), vol. ii, p. 



93, PI. II, fig. 7; also 1852, Geol. Rep. Iowa, Wise, and Minnesota, p. 597, 



PI. 5 R, figs. 7 b. Upper Burlington limest., Burlington, Iowa. 

 1880. S. granuliferus Wetherby, Journ. Cincin. Soc. Nat. Hist., PI. 16, figs. 3, 3 a. 



Kinderhook gr., Kentucky. 

 1858. S. matutinus Hall, Geol. Rep. Iowa, vol. i, p. 483, PI. i, fig. 2. Hamilton gr., 



New Buffalo, Iowa. 



1860. S. Oweni Hall, 13th Rep. N. York St. Cab. Nat. Hist., p. 111. Kinderhook 



gr., Rockford, Indiana. 



1861. S. papillatus Hall, Descr. New Crin. (Prelim. Notice), p. 18. Upper Burling- 



ton limestone, Burlington (a mere variety of S. dentatus). 



1865. S. robustus Shumard, Trans. Acad. Nat. Sci. Phila., vol. ii (Palaeozoic Foss. 



America), p. 397. Meek and Worthen, 1885, Geol. Rep. Illinois, vii, p. 514, 

 PI. 29, fig. 4. Keokuk limestone. Button-Mould Knob, Ky., and Sulphur 

 Springs, near Nashville, Tenn. 



1858. S. Swallovi Hall, Geol. Rep. Iowa, vol. i, Pt. II, p. 672, PI. 17, figs. 8 and 9. 



(?) St. Louis limestone. Missouri. 

 1869. S, WachsmutM Meek and Worthen (not 1866== Catillocrinus Wacbsmuthi), 

 Proc. Acad. Nat. Sci. Phila., p. 67 ; also Geol. Rep. Illinois, v, p. 437, PI. 2, 

 fig. .5. Lower Burlington limestone. Burlington, Iowa. 



1859. S. Wortheni Hall, Geol. Rep. Iowa, vol. i, Pt. ii, p. 560, PL 9, fig. 9. Upper 



Burlington limestone. Burlington, Iowa. 



PHIMOCRINUS Schultze. 



1866. Schultze, Monogr. Echin. Eifl. Kalk., p. 29. 

 1879. Zittel, Handb. d. Palaeoutologie, i, p. 350. 



1882. Oehlei-t, BuU. Soc. Geol. de France, Ser. 3, x, p. 353. 



Phimocrinus agrees almost completely with Symbathocrinus, 

 but it has five basals in place of three. It also has similar arti- 

 cular facets, which, in a like manner, form a stelliform pyramid, 

 of which, however, the summit plates have not been observed. 

 The anal opening is situated between two muscle-plates, and 



