OCR Text |
Show 355 some specimens in the collection too imperfect to be figured, than in the one from which the figure given on plate 1 was drawn. Locality and position.- Carboniferous limestone, at Eatlahwoke Creek, just west of the principal range of the Rocky Mountains, latitude 49° north, longitude 114° west. Genus SPIRIFER, gowerby. SPIEIFER KEOKUK, Hall? Plate 1, figs. 3, 3, a. Spirifer Keokuk, Hall ( 1853), Geol. Report Iowa, i, 642, pi. xx, figs. 3, a- d, and 2 d. Spirifer Keokuk, var., t6., 676, pi. xxiv, figs. 4, a, b, c, d. The specimens of this Spirifer in the collection* are very imperfect; but as far as their characters can be made out, they present no peculiarities by which they can be distinguished from the shell described by Professor Hall under the name S. Keokuk. Colonel Simpson, Mr. King, and Dr. Hayden have also brought, from dark- bluish and gray limestones at various localities in Utah and other far western districts, specimens of apparently the same shell. There is also in the Coal- Measures of the Western States a Spirifer that has been described by Professor Hall under the name S. opimus, in his Iowa Eeport .( and, as I think, more recently by Professor McChesney, under the name S. subventricosus), that seems to be very closely allied. Locality and position.- Gray Carboniferous limestone; Kootenay range of Rocky Mountains. Genus A* THYRIS, McCoy, 1844, = SPIRIGERA, d'Orbigny, 1847. ATHYRIS SUBTILITA, Hall ( sp.). Plate 1, figs. 2, 2 a. Terebratula Boysii, d'Orbigny ( 1842), Voy. dans l'Amlr. Me* rid., viii, 44, pi. iii, figs. 17- 19; ( not L'Eveilfe ( sp.), 1835). Terebratnla lubtilita, Hall ( 1852), in Stansbury's Report Exp. to Great Salt Lake, 409, pi. iv ( by error pi. ii), figs. 1, a, b, and 2, a, &.- Schiel ( 1855), Report Pacific R. R. Survey, ii, 108, pi. 1, figs. 2, a, &.- Davidson f ( 1856), Brit. Carb. Brach., 18, pi. 1, figs. 21 and 22.- Hall ( 1856), Report Pacific R. R., iii, 101, pi. ii, figs. 1 and 2.- Marcou ( 1858), Geol. N. Am., 52, pi. vi, fig. 9, a, b, c, d, e,/. Athyris subtila, Davidson ( 1856), British Carb. Brach., 86, pi. i, figs. 21 and 22, and pi. xvii, figs. 8- 10.- Salter ( 1861), Qr. Jour. Geol. Soc. Lond., 64, pi. iv, fig. 4. As nearly as can be determined from a single specimen of the shell uuder consideration, it appears to agree well with A. subtilita in form and general appearance. It is smaller, however, than the usual adult size of that species; but, like other species of the genus, that shell is known to vary considerably in size at different localities. In the Mississippi Valley, A. subtilita is usually regarded as being confined to the Coal- Measures and Permo- Carbouiferous beds; but the British examples cited above came from the Lower Carboniferous. We have in our Lower Carboniferous ( Chester group) a form described, by Professor Hall in the Iowa Report, under the name A. subquadrata, which |