66 THE PALEONTOLOGY OF MINNESOTA. 



I Isehadites. 

 1. SQUAMIFER Hall. 



1859. Dictyocrinus squamifer HALL. Paleontology of New York, vol. ili, p. 135, pi. 7A, flgs. 11, 13. 



1883. Seceptaculites squamifer HALL. Second Ann. Rep. N. Y. State Geologist, pi. 23, flgs. 1, 2. 

 1887. Ischadites squamifer HALL. Palaeontology of New York, vol. vi, p. 291, pi. 24, flgs. 1, 2. 



Formation and locality. Lower Helderberg ; Schoharie, New York. 



I. TESSELLATUS Winohell and Marcy. 



1861. Seceptaculites infundibulum HALL.* Keport of the Superintendent of the Geological Survey 



of Wisconsin, p. 16. 



1866. Ischadites tessellatus WINCIIELL and MARCY. Memoirs Boston Soc. Nat. Hist., vol. i, p. 85, 



pi. 2, flg.3. 



1867. Ischadites tessellattts HALL. Twentieth Rep. N. Y. State Cab. Nat. Hist., pp. 390, 395. 



1870. Seceptaculites formosus MEEK and WOUTHEN. Proc. Acad. Nat. Sci. Philadelphia, sec. ser vol 



xiv, p. 22. 

 1875. Seceptaculites formosus MEEK and WOUTHEN. Geological Survey of Illinois, vol. iv, p. 500, pi. 



24, fig. 1. 

 1875. Ischadites tessellatus GUMBEL. Abhandl. der. k. bayer. Akad. der Wissensch., bd. xii, p. 40. 



1884. Ischadites tessellatus HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 839. 



The pear-shaped form and the large spicular head-plates readily separate this from all other Amer- 

 ican species of the genus, except I. canadensis Billings ; which will probably prove to be a synonym. 



Formation and locality.- Niagara limestone; near Chicago, Illinois, and Racine, Wisconsin. 



I. CANADENSIS Billings. 



1863. Ischadites canadensis BILLINGS. Geology of Canada, p. 309, tig. 313, and p. 327 (not described). 

 1865. Eeceptaculites canadensis BILLINGS. Paleozoic Fossils, vol. i, p. 384, fig. 362 (not described). 

 1865. Eeceptaculites canadensis BILLINGS. Canadian Naturalist and Geologist, sec. sor. vol. ii, p. 191, 



flg. 10. 



1880. Seceptaculites canadensis ROMER. Letluea PaUeozoica, p. 289. 

 1884. Seceptaculites ?canadensis HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 84-1. 

 Probably identical with I. tessellatus, in which case this name will have precedence, provided, how- 

 ever, that a figure without a description is regarded as sufficient for establishing a species. 



Formation and locality. Niagara limestone ; township of Esquesing, Ontario, Canada. 



I. SUBTURBINATUS Hall. 



1863. Seceptaculites subturbinatw HALL. Transactions Albany Institute, vol. iv, p. 224. 



1879. Seceptaculites subturbinatus HALL. Twenty-eighth Rep. N. Y. State Mus. Nat. Hist., p. 103, 



pi. 3, flgs. 1-3. 

 1882. Seceptaculites subturbinatus HALL. Eleventh Rep. State Geologist of Indiana, p. 221, pi. 2, 



flgs. 1-3. 



1884. i Ischadites Iccenigii (partim) HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 836. 

 This species is regarded as a synonym of I. koznigii by Hinde (op. cit.}. 



Formation and locality. Niagara group ; Waldron, Indiana. 



I. HEMISPHEKICUS Hall. 



1861. Seceptaculites hemisphericum HALL. Report of the Superintendent of the Geological Survey 



of Wisconsin, p. 16. 



1875. Receptaculites ohioensis HALL and WHITFIELD. Paleontology of Ohio, vol. ii, p. 123, pi. 6, flg. 1 . 

 1882. Seceptaculites hemisphericum WHITFIELD. Geology of Wisconsin, vol. iv, p. 269, pi. 13, flg. 4. 

 1884. Ischadites Iccenigii (partim) HINDE. Quart. Jour. Geol. Soc. London, vol. xl, p. 836. 

 This is also regarded as a synonym of I. kcenigii by Dr. Hinde. 

 Formation and locality. Niagara limestone ; Eacine and Waulcesba. Wisconsin, and Yellow Springs. Ohio. 



Since this species was accompanied by a poor desrript inn. and without figures, we prefer to use the name I. tessellatus 

 for it. Dr Hinde (op. cit. p. 839) says regarding R. infuiuUhulttm. " in the absence of figures, mere verbal description, like 

 Hall's, of the fossils of this group Is quite insufficient for the recognition of species, more particularly when the character of 

 the fossil is so little understood by the author that he regards the base of the fossil as its summit, and i-lcr raw." Meek and 

 Worthen (Geol. Survey of Illinois, vol. iii. p. 302) also say that they were unable to identify "several allied forms already 

 named and described from these rocks, and not yet figured. " 



