CARBONIFEROUS SPECIES. 87 



the latter group, being beautifully punctate, as can be readily seen with a 

 common single lens, the punctures being so large as even to give the whole 

 surface of internal casts a beautiful granular appearance ; while casts of 

 the rostral cavity of the ventral valve show a deep mesial slit, left by a 

 well-defined mesial septum, a.s seen in fig. 1 c of plate 8. 



Locality and position. — The typical specimens were brought by Colonel 

 Simpson from a locality in Nevada, at latitude 40° N., longitude 115° 20' W.; 

 the other more gibbous specimens in the collections under consideration came 

 from White Pine County, twenty-five miles northeast of Hamilton, Ruby 

 Group, Nevada: all from light-colored Carboniferous limestone. 



A number of other specimens in the collection, from a light-grayish 

 limestone at the mouth of Weber Canon (see pi. 12, figs. 12, 12 a, 12 

 h, 12 c, 12 d), agree, so far as can be seen, in all respects with this species. 

 Some of them are compressed like the typical specimens, while others are 

 more gibbous, and agree exactly with those from the Ruby Group. 



Genus SPIRIFER, Sowerby. 



Spirifer cuspid atu.s, Martin? (.sp.). 

 Plate:), tigs. 11, 11a. 



Anomitcs cuspidahis, Martin (179G), Trans. Linn. Soc, IV, 44, pi. iii, fig.s. 1-6. 



Conchyliolithus {Anomites) cuspidatus, Martin (1809), Petref. Derb., I, 10, pi. 40, fig. 34, 

 and pi. 47, fig. 5. 



Spirifer cuspidatus, Sowerby (1816), Min. Couch., II, tab. 120, figs. 1-3 ; and of numer- 

 ous later authors. 



Delthyris cuspidatus. Keiferst. (1824), Naturges. des Erdk., II, Oil. 



C)jrtia simplex, McCoy (1844), Synop. Carb. Foss. Ireland (not of Phillips). 



Ci/rtia cuspidata, McCoy (1855), Brit. Pal. Foss., 466. 



Of the form I have referred with doubt to the above-mentioned species, 

 there is but one distorted specimen and a part of another in the collection. 

 It seems to have had, before distortion, exactly the form, size, and surface- 

 characters of a medium-sized individual of S. cuspidatus, excepting that its 

 high area is arched a little backward, instead of being merely vertical or 

 slightly arched forward, as seems to be generally the case with S. cuspidatus. 

 As this, however, is doubtless a more or less variable character, unless 

 known to be constant in a large number of specimens, and to be accom- 



