FOSSILS OF THE DEVONIAN. 1535) 
by Mr. Meek were small, but do not differ from specimens of the same size 
found at Newark Mountain or specifically from the larger shells that are 
identical with examples of the species found in New York and also in Eng- 
land. 
Formation and localities.—Central and upper portions of the Devonian 
limestone, Newark Mountain, and at The Gate, northwest of Eureka, Ne- 
vada. 
Spirifera raricosta Conrad (Sp.). 
Plate iv, figs. 2, 2a; pl. xiv, fig. 12. 
Delthyris raricosta Conrad, 1842. Jour. Acad. Nat. Sci. Philad., vol. viii, p. 262, pl. 
xiv, fig. 18. 
undulatus Vanuxem, 1842. Geol. Rep. Third District New York, p. 132, fig. 3. 
Spirifera raricosta Billings, 1861. Can. Jour., vol. vi, p. 258, figs. 71-73 of p. 259; Pal. 
Fossils, 1874, vol. ii, pt. 1, p. 47, pl. 3A, figs. 5, 5 a, b. 
Hall, 1867. Pal. New York, vol. iv, p. 192, pl, xxvii, figs. 30-34, pl. 
xxx, figs. 1-9. 
Nicholson, 1873. Pal. Prov. Ontario, p. 82. 
A species closely allied to this, if not identical, occurs in the lower 
fossiliferous horizon of the Devonian limestone. It differs in not having 
quite as distinct concentric striz, and also in the absence of the prominent 
septum shown in casts of the ventral valve of specimens from the Schoharie 
erit of New York. These are characters that are variable in the New York 
forms, and do not afford data for the establishment of a distinct peo: on 
the examples thus far obtained in Nevada. 
At the East this species ranges through the Schoharie grit and Cor- 
niferous limestone of the Upper Helderberg Group, and its known geo- 
graphical extension carries it west from New York across the State of Ohio 
to Southern Indiana and northwest into Canada West. 
A larger series of specimens from Lone Mountain, collected a year 
after the above was written, show a gradation in form from Spirifera rari- 
costa to S. duodenaria, the constant differences in the median sinus and fold 
alone serving to distinguish, in external characters, the two species. 
Formation and localities—Lower horizon of the Devonian limestone, 
Comb’s Peak, Eureka District, and Lone Mountain, 18 miles northwest of 
Eureka, Nevada. 
