DEVONIAN SPECIES. 41 



Mr. IIa<:,nio .-ilso fdund it with other Devonian fossils, ni, Fossil Hill, White 



Pine District, Nevada, in the silver-bearing Devonian beds; the formation 



being the same at these two localities. 



Spiiufee Engelmanni, Meek. 



Plate 3, figs. 3, 3 a, 3 6, 3 c (and 3 rf, 3 e, 3/?). 



Spirifera Engelmanni, Meek (1860), Proceed. Acad. Nat. Sci. Philad., XII, 308. 

 Sj)irifer Engelmanni, Meek (1870), Col. Simpson's Report Expl. across the Great Basin 

 of Utab, 346, pi. 1, figs. I a, b, c (not S. Engelmanni, Meek and Wortlien). 



Shell rather small, somewhat gibbous, subsemicircular, or approach- 

 ing subtrigonal in general form, with the greatest breadth on the hinge-line; 

 lateral extremities rather acutely angular; anterior lateral margins with 

 outline usually straightened and converging rapidly from the lateral extrem- 

 ities to the middle of the front. Ventral valve more convex than the other, 

 its greatest prominence being at or near the beak, which is abruptly pointed 

 and more or less incurved; area generally rather high, well defined, and 

 standing nearly at right angles to the plane of the valves, but always arch- 

 ing backward with the beak; foramen higher than wide; mesial sinus nar- 

 row and shallow, but extending to the apex of the beak, smoothly rounded 

 within, and bounded on each side by a. plication that is a little more prom- 

 inent than any of the others; lateral slopes each occupied by about seven 

 to ten simple costse. Dorsal valve moderately convex, the greatest con- 

 vexity being near the middle ; mesial fold narrow, flattened, or more or less 

 rounded, and, like the sinus of the other valve, without costse or plications ; 

 lateral slopes with costae as in the other valve; beak scarcely distinct from 

 the cardinal margin. Fine surface-markings and internal characters 

 unknown. Figs. 3, 3 a, 3 b, and 3c represent the type, while the others are 

 only referred doubtfully to this species. 



Length, 0.57 inch; breadth, about 0.82 inch; convexity, about 0.50 inch. 



Specimens of this species with an elevated beak and area have much 

 the general appearance of the last, and, when not well preserved, might be 

 confounded with it by a careless observer. The two species, however, are 

 very distinct, and may be readily separated by the larger costos of the form 

 under consideration, which also differs in never having any cost;B occupy- 

 ing the mesial fold and sinus. 



