78 PALEONTOLOGY. 



are in a condition to sliow the muscular or reniform impressions, nor very 

 clearly the form of the cardinal process. 



Generally, on somewhat worn specimens, the fine striae are so nearly 

 obsolete that the surface presents the appearance, at a first glance, of being 

 entirely smooth ; but even these specimens nearly always show remains of 

 the striaj on the more protected parts, while, where the surface is well pre- 

 served, they are always seen distinctly defined on all parts. 



I am not acquainted with any other species nearly enough allied to 

 this to render a comparison necessary. 



Locality and j)osition. — The original type-specimens of this species were 

 brought by Colonel Simpson's party from latitude 39° 51' N., longitude 

 115° 10' W., near the center of the eastern margin of Nevada. Those in 

 Mr. King's collection came from further west, in the Ruby Group, and Ma- 

 hogany Peak, Egan Range ; the matrix being, in all cases, a light-colored 

 limestone. I have never seen it from any other localities, and know of no 

 nearly allied form in the rocks of the Mississippi Valley. Its associates are 

 always well-marked Carboniferous types. 



Tkoductus LONGispiNU.s, Sowcrby. 



Plate 8, fiss. 4, 4 a. 

 I'roiJuctiis iDifiispinus, Sowcrby (1814), Miu. Cjucb., I, 151, pi. Ixviii, ftg. 1. — Do 



Kotiiiick (1847), Desciip. An. Foss. Ciirb. Belg., 187, pi. xii, figs. 11 a, b, 



aud pi. xii bis, fig. 2.-;-Diivi(lson (1853), Introd. Brit. Foss. Bracb., pi. ix, fi.;. 



221 ; also (ISGO), Monogr. Scottisb Garb. Brac'.i., pi. ii, figs. 10-19; aud (1801) 



Brit. Gaib. Brach., 154, pi. xxxv, figs. 5-17. 

 Productus Fleminf/ii, Sowerby (1814), Miii. Goucb., 1, 154, pi. G8, fig. 2.— De Kouinck 



(1847), Mouogr. Prod., [d. x, fig. 2.— McGoy (1855), Biit. Pal. Foss., 401. 

 rroductus .spinosus, Sowerby (1814), Min. Goiicb., 1, 157, pi. 09, fig. 2. 

 Froductus lohatns, Sowcrby (1821), ib., IV, 10, pi. 318, figs. 2-0.— Von Bucb (1841), 



Ver. Konigl. Akad. Wiss., Tbeil I, 32, pi. ii, tig. 17.— De Vcrneuil (1845), 



Gcol. Uuss. and Ural Mts., II, 200, pi. xvi, fig. 3, and pi. xviii, fig. 8. 

 rroducUis clegans, Davereux (1833), Gonst. Gcol. de la Prov. de Liege, 272. 

 Froducta setom, Phillips (1830), Geol. Yorks., H, 214, pi. viii, figs. 9 and 17. 

 Froductus Cai)«c»', d'Orbigny (1843), Pal(iont.Voy. Am. Mcrid., 50, pi. iii, figs. 24-20. 

 Froductus inbcrofius, Dc Kcy-serling (1S40), Pctsciiora Liud, 208, pi. iv, fig. 0. 

 Froductus Waba.skensis, Norwood and Prattcn (1854), Jonr. Acad. Nat. Sci. Pliilad., Ill, 



pi. i, fig. 0. 

 fFioductus splcndens, ib., pi. i, fig. 5. 



The specimens of the little shell that I have, with doubt, referred to the 

 above species, are not in a very good state of preservation ; but, as far as 

 their charactex's can be made out, they seem to agree at least with forms 



