FOSSILS OF THE CARBONIFEROUS. 220 
LAMELLIBRANCHIATA. 
The occurrence of a number of species of this class in the Carbonifer- 
ous Group, in the region of the Rocky Mountains, is unusual, as heretofore 
it has been but sparingly represented. 
In 1852 Prof. J. Hall (Stansbury’s Expedition to the Great Salt Lake, 
p- 412) described a few species, viz: Avicula=Pseudomonotis curta, Tellino- 
mya protensa (probably belongs to the genus Modiomorpha), Allorisma 
terminalis, Cypricardia occidentalis, Nucula arata. 
Of these the last three species were obtained from Eastern Nebraska or 
the Mississippi Valley region. To the first two may be added twenty-two 
species mentioned by different authors: 
Marcou, J., 1858. Geology of North America, p. 44. Myalina Apachesi. 
Meek, F. B., 1860. Preliminary Notice. 1876. Report Explorations Across the Great 
Basin of Utah, Simpson, p. 354. Aviculopecten Utahensis. 
White, C. A., 1874. Preliminary Notice. 1875. Explorations and Surveys West of 
the 100th Meridian, vol. iv, pt.1, p.146. Aviculopecten occidentalis, A. Corey- 
anus, A. McCoyi, A. ? interlineatus, Pinna peracuta?, Monopteria Marian, My- 
alina, sp., M. ? Swallovi, Bakevellia parva, Schizodus Wheeleri, Allorisma 
subcuneata, var. Also, in Appendix to Supplement of vol. iii of the same 
Survey, 1881, p.xxv. Myalina Permiana and Pleurophorus subcostatus. 
Whitfield, R. P., 1875. Carroll, Montana, to Yellowstone National Park, Ludlow, p. 
143. Pinna Ludlovi. 
Meek, F. B., 1877. Geological Exploration of the Fortieth Parallel, vol. iv, p.96. A. 
occidaneus. 
Two other species are described as from the Carboniferous, but they 
are more properly referred to the Devonian by Messrs. Hall and Whitfield. 
Hall, J.,and Whitfield, R. P.,1877. Geological Exploration of the Fortieth Parallel, vol. 
iv, p. 273. Aviculopecten Weberensis, A. curto-cardinalis, A. parvulus, Mya- 
lina aviculoides, M. Permiana, Sedgwickia ? concava, Cardiomorpha Missou- 
riensis. 
The latter species, Cardiomorpha Missouriensis, although described from 
the Coal Measures of Missouri and Illinois, is, in Nevada, found in the strata 
at the summit of the Devonian and is not, there, a Carboniferous species; 
with this exception, all of the twenty-four species heretofore described are 
from the upper portions of the Carboniferous Group, usually referred by 
authors to the Coal Measures. From the latter horizon but one species is 
15 cD W 
