OF NORTH AMERICA. 
49 
Observations. — This species resembles the young of the Orthis resupinata Martin; but it differs in 
having an oval form , while the other is transverse. 
Locality. — This species is rare; 1 found only one specimen at Pecos village, New^ Mexico. 
Explanation of figures. -- Plate VI , fig. 14. View' of dorsal valve. 
M VI, fig. 14 a. Same. View of the ventral valve. 
» VI , fig. 14 b. Same. View of the beak. 
ORTHIS CRENISTRIA Phill. 
Description. — ((Surface of the valve radiated w'ith strong divaricating striae , crenulatcd by the lines of growth)). 
See: Geology of Yorkshire; Part II, the Mountain Limestone district, p. 216; pi. IX, fig. 6. I have not figured this 
species my specimens being loo imperfect; but several of my fragments resemble so much the figure of the 0. cre- 
nistria of Phillips, that, aided by the advice of de Koninck, 1 do not hesitate to regard them as identical. 
Locality. — Is quite common in company with the Prodmtus semi-reticulatus the P. Cora and the 
Ter. subtilita at the village of Pecos. 
SPIRIFER STRIATUS Mart. 
Plate VII, fig. 2,2 a. 
Description. — This species is well known and found wherever the Mountain Limestone exists. The following 
is the description of it given by William Martin in 1793. n Conchyliolithus (striatus) Anomice — a fossil shell — valves 
((Convex, semi-orbicular, longitudinally striated; the ^'nce strongly marked, close and numerous. Beak of the larger 
((valve pointed, and curved over the hinge, which extends, on a straight line, the w'hole breadth of the shell. 
((Margin obsoletely waved. A convex fold dow’n the middle of the smaller valve, proceeding from the valve of the 
((margin to the beak — in the large vj^lve, a concave fold. The folds slight; that of the larger valve scarcely dis- 
<( tinguishable. A triangular aperture under the beak of the large valve ». (See: Figures and Descriptions of Petri- 
factions collected in Derbyshire, by William Martin, plate 23; Wigan, 1793. Also, British Paleozoic Fossils, by M*" 
Coy, p. 422; London, 1855. Also, FossUes du Carbonifere de Belgique , by de Koninck, p. 256; Liege, 1844. Also, 
Pale'ontologie de la Russie et de I'Oural, by de Verneuil , p. 167; Paris, 1845.) 
Locality. — This Spirifer is oiie of the largest and also one of the most characteristic fossils 
of the Carboniferous epoch. It is quite common in the Lower Carboniferous of the States of Ohio, 
Kentucky, Tennessee, Indiana^ Illinois, Iowa, Missouri and Arkansas; and it forms a complete bed 
of limestone afoot thick, in the Mountain Limestone of Pecos village. This bed of Spirifer striatus is 
separated from that of the Productus semi-reticulatus by only twenty feet of limestone, in which the 
Terebratula subtilita is very common. I found it also at the summit of the Sierra de Sandia, 12,000 feet 
above the sea-level, and also at the village of Tigeras, New Mexico. I have received this spe- 
cies from persons who had found it near Great Salt Lake city, Utah; in Shasta county, California; 
and at Vancouver island. 
Explanation of figures. — Plate VII, fig. 2. Specimen from Pecos village, vdew of dorsal valve. 
» VII , fig. 2 a. Same , ventral valve. 
SPIRIFER STRIATUS var. TRIPLICATUS. 
Plate VII, fig. 3. 
Description. — In common with ail species widely distributed over the Earth’s surface, the Sp. striatus presents 
several varieties. I saw several thousand specimens in the Rocky mountains lying in the same strata mingled to- 
gether, which when studied separately would seem to belong to at least three distinct species: the true Sp- striatus ; 
a second more transverse and with an area more developed than the Sp. striatus, and which D. D. Owen doubts 
is identical with the Spirifer fasciger? lastly a third, having the same general form as the Sp. striatus^ distinguished 
7 
