176 PALEONTOLOGY OF THE EUEEKA D1STEICT. 



Surface nearly smooth, a few obscure lines of growth alone showing 

 on the cast or matrix. 



The anterior adductor muscular scar is of medium size, and has a low' 

 ridge and sulcus posterior to it that start near the beak and extend nearly 

 to the basal margin. 



Dimensions: height at anterior end, 1.75 cm ; near posterior end, 2 cm ; 

 length, ll cm . 



This form differs from the preceding species in its more slender form, 

 the absence of a well-defined byssal furrow, and the more attenuate anterior 

 extremity. 



Formation and locality. Lower Devonian of Brush Peak, Eureka Dis- 

 trict, Nevada, and also at the same horizon on Lone Mountain, 18 miles 

 northwest of Eureka, Nevada. 



Sanguinolites rigidus W. & W. (Sp.) 

 Plate xvi, fig. 6. 



Cypricardiaf rigida White & Whitfield, 1862. Proc. Boston Soc. Nat. Hist., vol. viii, 



p. 300. 



Edmondiaf bicarinata Winchell, 1S63. Proc. Acad. Nat. Sci. Philad., vol. xv, p. 13. 

 Sanguinolites rigidi Hall, 1870. Prelim. Notice Lam. Shells, p. 44. 



rigidus Hall, 1883. Pal. N. Y., vol. v, pt. 1, Plates and Descriptions, p. 

 16; pi. Ixvi, figs. 1-19. 



The relative stratigraphic position of this species in the Chemung 

 Group of New York and the Upper Devonian beds of The Gate, northwest 

 of Eureka, is the same; and direct comparison with specimens from the 

 Burlington sandstones of Iowa and the Chemung shales of New York, shows 

 the two forms to be specifically identical. 



Sanguinolites ? Sanduskyensis Meek. 

 Plato v, fig. 4. 



Sanguinolites? SandusTcyensis Meek, 1871. Proc. Acad. Nat. Sci. Philad., vol. -g^iii, 

 p. 68. Ibid., 1873. Geol. Surv. Ohio Pal., vol. i, pt. 2, p. 209, pi. xviii, fig. 3. 



Compare Modiomorpha linguiformis Hall. Pal. N. Y., vol. v, pt. 1, Plates and Descrip- 

 tions, p. 12, pi. xxxiv, figs. 15-17, and M. Hyalea, p. 13, pi. xli, fig. 28. 



The external form and characters of the shell before me agree with 

 those described by Mr. Meek, as shown in his figure. 



