PALH ONTOLOGY. 127 
village, east of Santa Fé, and is equally abundant in the Coal measures of Kansas, Missouri, 
and Ohio. Wherever found it is indicative of the presence of the Goal measures or their 
equivalents, and, with the other evidence which has been cited, proves conclusively that the 
limestone at Pecos and neighboring localities is not the equivalent of that which underlies the 
Coal measures throughout the southern portions of the coal basins of Nova Scotia and the Mis- 
sissippi valley, usually considered identical with the Mountain limestone of Europe. It also 
constitutes one of the indices of the Upper Carboniferous date of the limestone occupying so 
large a surface west of the Little Colorado, of which the exposures at Camp 70, Cascade river, 
Partridge and Cedar creeks, and east of the San Francisco mountains, are fully described in 
the preceding chapters. This shell, so widely distributed, both geographically and vertically, 
affords conclusive proof that throughout the greater part of New Mexico an open sea prevailed 
during the entire continuance of the Carboniferous epoch. The Upper Carboniferous lime- 
stones, in their great thickness and uniformity of character, indicate the uninterrupted prev- 
alence in this region of the physical conditions represented by the numerous, but thin and 
widely separated, calcareous bands which are a constant feature in the structure of the pro- 
ductive Coal measures in the Mississippi valley. Specimens collected by the writer on the 
banks of the Colorado exhibit the spiral cones of the interior with great distinctness. 
SPIRIFER. Sowerby. 
SPIRIFER CAMERATUS. Mort. Amer. Jour. Science, vol. 29, p. 150, pl. I, fig. 3. 
This fossil, so characteristic of the Coal measures of the Mississippi valley, occurs abundantly 
in the limestones about Santa Fé and Pecos village, New Mexico, and in the limestones of the 
Carboniferous series in Kansas and Missouri. 
I have collected the same fossil in various parts of eastern Ohio and western Porinsylvania, 
It is liable to considerable variation in size, and also, to a less degree, in the size and arrangement 
of its plications. It is not, however, so like other species as to be easily confounded with them; 
and from its abundance in most of the localities where it is found, and its wide distribution, it 
is one of the most valuable guides in the identification of strata. 
We did not find it in the Carboniferous limestones west of the Rio Grande, although its 
associates, Spirifer lineatus, Spirigera subtilita, &c., are abundant. 
This is the shell figured by Mr. Marcou, (Op. cit. p. 49, pl. VII, fig. 3,) under the name of 
S. striatus, var. triplicatus. Both forms given by him are presented in many localities where 
this fossil exists. Such is especially the case in the series which I have collected in Ohio. 
The largest, most inflated, and least angular specimens resemble S. striatus, but by far the 
greater number depart very widely from it. Even when most like S. striatus, the form is more 
angular and the number of plications less. In S. striatus these vary from 80 to 100 in each 
valve, while in all the specimens which I have the number is from 60 to 7). Roemer and Hall, 
who describe this species under different names, regard it as distinct from S. striatus. 
SprrireR RockyMonTani. Marcou. Geol. N. Amer., p. 50, pl. VII, jigs. 4—4e. 
This is a distinct and beautiful species, of not uncommon occurrence in the Carboniferous 
limestones of New Mexico. Dr. Hayden has also found it in the Black Hills, Nebraska. 
SPIRIFER LINEATUS. De Konninck. 
This species is even more widely distributed than S. cameratus, being common to Europe 
and America, and found over all parts of our continent, wherever the Carboniferous series is 
developed. It is quite common in the cherty limestone west of the Little Colorado, occurs 
again on our route in the limestones of the vicinity of Santa Fé, and in Kansas and Missouri. 
I have also collected great numbers of specimens of it in the Coal measures of Ohio. — 
