FOSSILS OF THE DEVONIAN. 139 
Subgenus MARTINIA McCoy. 
Spirifera (Martinia) glabra Martin. 
For list of synonyms, see British Carboniferous Brachiopoda, Davidson, vol. ii, p. 59- 
Spirifera M. glabra is mentioned by Mr. Davidson in his monograph of 
the British Carboniferous Brachiopoda, p. 62, as occurring in Devonian rocks, 
and he also states that he had specimens from the Devonian of Devonshire 
which appeared undistinguishable from those in the Carboniferous limestone. 
Before reading this observation we had compared the Devonian specimens 
from Nevada with examples of S. (JL) glabra from the Carboniferous lime- 
stone of England, and also with Mr. Davidson’s beautiful illustrations of the 
species, and concluded that they were at the most but a variety of the same 
species, and it is only for convenience in referring to the Nevada Devonian 
form that a varietal name is proposed. 
Spirifera (M.) Franklini Meek, 1869 (Trans. Chicago Acad. Sci., vol. i, 
p. 107, pl. xiv, fig. 12), is, as mentioned by Mr. Meek, closely related to S. 
(M.) glabra, and with the original specimen before me to compare with the 
Nevada shells and Mr. Davidson’s figures of the species, it scarcely appears 
to be more than a variety, if even that, of S. (JL) glabra. Mr. Meek sepa- 
rated it from 8. (M. )glabra on account of having the lateral margins of the 
area of the ventral valve extending out part way parallel to the hinge mar- 
gins, instead of sloping regularly from the beak to the extremities of the 
hinge. In the variety to be next described both characters occur on the 
area of the ventral valve on different specimens, so that it is scarcely a 
good specific distinction. 
Spirifera (M.) glabra, var. Nevadensis, n. var. 
Plate iii, fig. 5; pl. xiv, figs. 14, 14a, b. 
The range of variation among the specimens in the collection is con- 
siderable, as they differ in the strength and angularity of the mesial fold 
and sinus, and the depression along the middle of the mesial fold of the 
dorsal valve may be strong as in the example illustrated on plate xiv, fig. 
14, or entirely absent even in large-sized specimens. Some shells are also 
