scHDCHEKT.] INDEX AND BIBLIOGRAPHY. 187 



Conchidium multicostatum Hall. Xia.yara (Sil.). 



Puiitiiiuerus iiiulticostatus Hall, Gcol. Survey Wisconsin; Kej). I'rogress, 1860, 



p. 1;— Twentieth Rep. New York State Cab. Nat. Hist., 1867, p. 373, pi. 13, 



figs. 22-24. 

 Conchidium multicostatum Hall and Clarke, I'al. New ^Ork, \'III, I't. II, 1895, 



pi. 64, fig. 6; pi. 66, fig. 10. 

 Loc. Wauwatosa and Waukesha, Wisconsin. 



('oiicliidium nettelrotlii Hall and Clarke=0. knighti. 



Conchidium nysius (Hall aucl Whitfield). Niagara (Sil.). 



Pcntanierus nysins var. ciassicosta Hall and Whitfield, Twenty-fourth Rep. New 

 York State Cab. Nat. Hist., 1872, p. 184; — Twenty-seventh Rep. Ibidem, 

 1875, pi. 10, iigs, 4-7. — Nettelroth, Kentucky Fossil Shells, Mem. Kentucky 

 Geol. Survey, 1889. p. 60, pi. 28, iigs. 5-8. 



Pentamerns nysius var. tenuicostatus Nettelroth, Ibide^i, 1889, p. 60. 



Couchidium nysius Hall and Clarke, Pal. New York, VIII, Pt. II, 1893, p. 235, 

 pi. 64, figs. 1, 8, 27. 



Loc. Louisville, Kentucky. 



Ois. See C. teimicostatuni. 



Conchidium obsoletum Hall and Clarke. Niagara (Sil.). 



Conchidium obsoletum Hall and Clarke, Pal. New York, YIII, Pt. II, 1895, pi. 



67, ligs. 8, 9. 

 Loc. Genoa, Ottawa County, Ohio. 



Conchidium occidentale Hall. Guelph (Sil.). 



Pentamerns occidentalis Hall, Pal. New York, II, 1852, jj. 341, pi. 79, figs. 1,2. — 

 Billings, Geol. Canada, 1863, p. 337, fig. 341.— Nicholson, Pal. Prov. Ontario, 

 1875, p. 67, fig. 35.— Whitfield, Geol. Wisconsin, IV, 1882, p. 314, pi. 17, fig. 10; 

 pi. 23, figs. 1, 2.— Hall and Clarke, Pal. New York, VIII, Pt. II, 1893, p. 239. 



Conchidium(?) occidentalis Hall and Clarke, Ibidem, 1895, pi. 67, figs. 1-5. 



Loc. Gault and Guelph, Ontario ; Point St. Vital, Lake Huron ; AVilliamstown, 

 Wisconsin. 



Conchidium(?) salinense (Swallow). "Base of Chemung" (Dev.). 



Peutamerus salinensis Swallow, Trans. St.' Louis Acad. Sci., I, 1860, p. 652. — 



Keyes, Geol. Survey Missouri, 'V, 1895, p. 104. 

 Lav. Moniteau County, Missouri. 

 Ofe.s. The geological horizon is prol>ably Corniferous or Hamilton. 



•Conchidium scoparium Hall and Clarke. Guelph (Sil.). 



Conchidium scoparium Hall and Clarke, Pal. New York, VIII, Pt. II, 1895, pi. 



67, figs. 6, 7. 

 Loc. Durham, Ontario. 



Conchidium tenuicostatum (Hall and Whitfield). Niagara (Sil.). 



Pentamerns nysius var. tenuicosta Hall and Whitfield, Twenty-fourth Rep. New 

 York State Cab. Nat. Hist., 1872, p. 184 ;— Twenty-seventh Rep. Ibidem, 

 1875, pi. 10, figs. 1-3. 



Pentamerus complanatus Nettelroth, Kentucky Fossil Shells, Mem. Kentucky 

 Geol. Survey, 1889, p. 53, pi. 27, figs. 14-16. 



Conchidium tenuicostatus Hall and Clarke, Pal. New York, VIII, Pt. II, 1893, 

 p. 235, pi. 64, figs. 3-5. 



Loc. Louisville, Kentucky. 



Ohs. P. nysius is described as consisting of two varieties. If these varieties are 

 species, as pointed out by Nettelroth, then P. nysius will be based upon and 

 supplant variety crassicosta, while variety tenuicosta must be elevated to 

 specific rank. P. complanatus Nettelroth, therefore, becomes a synonym for 

 C. tenuicostatum, as both are established upon the same specimens. 



