1889.] NATURAL SCIENCES OF PHILADELPHIA. 309 



Naticopsis genevievensis Meek and Worthen, 1866. Proc Acad. 

 Nat. Sci. Phila., p. 268. Kaskaskia Limestone. Syn. of Sp>haero- 

 doma littonana (Hall). 



Macrochilus hamiltonm Hall, 1862. loth Reg. Rep. N. Y. State 

 Cab., p. 49. Hamilton Gr. Perhaps a Holopea. Certainly does 

 not belong to the group under which it was described. 



Macrochilia hildrethi (Conrad). Phectostylus hildrethi Conrad, 

 1842. Jonr. Acad. Xat. Sci. Phila. Simply an imperfect natural 

 cast of a form resembling S. paludinceformis (Hall). Coal Meas. 



Macrochilus inhabile (Morton). Fususf inhabilis Morton, 1836. 

 Am. Jour. Sci., vol. XXIX, p. 160. Syn. of Sph. primogenia 

 (Conrad). 



Macrochilus intercalare Meek and Worthen, 1860. Proc. Acad. 

 Xat, Sci. Phila., p. 467. Syn. of Sph. medialis (M. & W.) 



Macrochilus macrostomum Hall, 1862. 15th Reg. Rept. X. Y. 

 State Cab., p. 49. Belongs not to this group. Probably a Holopea. 



Macrochilus rnissouriense Swallow, 1858. Trans. St. Louis Acad. 

 Sci., vol. I, p. 201. Described from imperfect casts. Coal Measures. 



Solenidcus planus White, 1881. Expl. and Sur. W. 100 Merid., 

 Supp. to vol. Ill, p. XXIX. Syn. of S. newberryi (Stevens). 



Macrochilus primaevium Hall, 1876. Illus. Dev. Foss., pi. xii. 

 Imperfect casts. 



Macrochilus pulchellum Meek and Worthen, 1860. Proc. Acad. 

 Xat, Sci. Phila,, p. 467. Syn. of Sph. medialis (M. and W.) 



Macrochilus spiral um McCoy. Xot American. Reported by 

 Swallow. 



Macrochilus ventricosum Hall, 1858. Geol. Iowa, vol. I, p. 718. 

 Preoccupied by Goldfuss. Syn. of S. brevis White. 



