248 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 
IsorELus GiGas Dekay. 
Plate 1, fig. 1, 2; Plate 2, fig. 2-5; Plate’ $) tga 
Isotelus gigas Dekay, Ann. Lyceum nat. hist. N. Y., 1824, 1, p. 176, pl. 12, 
fig. 1. Green, Monthly Amer. journ. geol., 1832, 2, p. 560; Monog. 
trilobites N. Amer., 1832, p. 68, casts 21, 22. Milne Edwards, Crustacés, 
1840, 3, p. 298. Vanuxem, Rept. Third geol. dist. N. Y., 1842, p. 46, 
fig. 1. Emmons, Rept. Geol. dist. N. Y., 1842, p. 389, fig. 1. Hall, 
Pal. N. Y., 1847, 1, p. 231, pls. 60-63. Emmons, Amer. geol., 1855, 1, 
pt. 2, p. 215, pl. 16, fig. 12. W.B. Rogers, Geol. Penn., 1858, 2, p. 819, 
fig. 610. Miller, Cincinnati quart. journ. sci., 1874, 1, p. 188. Clarke, 
Pal. Minn., 1897, 3, pt. 2, p. 701 (partim) fig. without number. Weller, 
Pal. N. J., 1902, 3, p. 192, pl. 14, fig. 6, 7 (non 5). Raymond and Narra- 
way, Ann. Carnegie mus., 1910, 7, p. 53, pl. 15, fig. 1, 2. Raymond, 
Trans. Roy. soc. Canada, 1912, ser. 3, 5, sect. 4, pl. 2, figs. 7, 8; pl. 8, 
fig. 6. 
Isotelus planus Dekay, Ann. Lyceum nat. hist. N. Y., 1824, 1, p. 178, pl. 13, 
fig. 7. Green, Monthly Amer. journ. geol., 1832, 2, p. 560; Monog. 
trilobites. N. Amer., 1832, p. 68, cast 23. 
Isotelus cyclops Green, Monthly Amer. journ. geol., 1832, 2, p. 560, pl., fig. 7; 
Monog. trilobites N. Amer., 1832, p. 69, cast. 24. 
Tsotelus megalops Green, Monog. trilobites N. Amer., 1832, p. 70, cast 25. 
Isotelus stegops Green, Monog. trilobites N. Amer., 1832, p. 71, casts 26, 27. | 
Isotelus jacobus Clarke, Pal. Minn., 1897, 3, pt. 2, p. 706, footnote. 
? Asaphus platycephalus Stokes, Trans. Geol. soc. London, 1823, ser. 2, 1, © 
pl. 27, no description. Buckland, Geol. and min., 1837, 2, p. 73, pl. 45, | 
fig. 12; Ibidem, 1867, pl. 63. 
Asaphus platycephalus Bronn, Lethaea geogn., 1835, 1, p. “Ls, pl. 9, fig. 3; 
Ibidem, 1851-1856, 1, p. 632, pl. 9, fig. 8; pl. 9, fig. 5. Burmeister, Die 
p. 110, pl. 2, fig. 12. Walcott, Bull. M. C. Z., 1881, 8, p. 198, pl. 2, fig. 9. | 
Asaphus gigas Dalman, K. Svensk. vet. akad. Handl., 1826, p. 276; Om Palaea- 
derna, 1827, p. 91; Ueber die Palaeaden, 1828, p. 70. 
Asaphus planus Dalman, K. Svensk. vet. akad. Handl., 1826, p. 276; Om 
Palaeaderna, 1827, p. 91; Ueber die Palaeaden, 1828, p. 70. | 
Asaphus megistos Billings, Geol. Canada, 1863, p. 184, fig. 182. 
Brongniartia isotelea Eaton, Geol. text book, 1832, p. 33, pl. 2, fig. 12. 
The following have been erroneously referred to this species:— 
Isotelus gigas Portlock, Geol. rept. Londonderry, 1848, p. 295, pl. 7, fig. 1” 
pl. 8, fig. 1. McCoy, Synopsis Silurian foss. Ireland, 1846, p. 53. Brog) 
ger, Bihang K. Svensk. vet. akad. Handl., 1886, 11, p. 31, pl. 1, fig. I) 
(= Isotelus platyrhachis Sremhart, teste Schmidt). Clarke, partim, Pal 
Minn. 3, 1897, pt. 2, p. 703, fig. 5 (= Isotelus iowensis). Weller, Pal 
