102 
GEOLOGICAL REPORT—THIRTY-FIFTH PARALLEL. 
These shells vary from elliptical or depressed globose to rotund and inflated forms. The area 
is often inconspicuous, and the beaks of the two valves are nearly equally prominent. The 
surface of the specimens is in general somewhat exfoliated, and presents a striato-punctate 
appearance. Sometimes the concentric and radiating stride are nearly equal in strength ; and 
the punctte or bases of the small tubular spines are scarcely perceptible. In better preserved 
specimens the fimbriated character is conspicuous. 
The form and essential characters possessed by these specimens leave no doubt of their identity 
with the European species to which they are referred. 
Locality. —Pecos village, New Mexico, associated with the preceding species. This- species is 
common in the carboniferous limestone of Europe. 
SPIRIFER KENTUCKENSIS.—Plate II, figs 10, 11. 
Spirifer Iventuckensis, Shumard, Geological Report of Missouri, 1855, page 203. 
Spirifer octoplicatus, Hall, Stansbury’s Report, 1852, plate IV, fig 4. 
Shell subtrigonal or semicircular, more or less elongate, gibbous, with from four to six plica¬ 
tions on each side of the mesial sinus, plications rounded, beaks remote; beak of the dorsal 
valve very prominent and slightly incurved; area large; surface marked by closely imbricating 
concentric strife, which are studded with minute granulations. 
Specimens of this species from different localities show some variations; those from Weston, 
in Missouri, being more gibbose, with the plications less angular than those from Pecos village.* 
Dr. Shumard says of this species, that it has from “ six to nine plaits on each side of the 
mesial sinus.” I have not been able to see specimens with more than six plications on each 
side; though it is not improbable that this character may undergo much variation with age. 
This species resembles the Spirifer octoplicatus of Sowerby, to which I formerly referred it 
with doubt. It bears some relation to Sp. crispus, Dalman, but is less pointed at the extremi¬ 
ties, the plications are less angular, and the concentric laminae less abruptly arched; while the 
minute granulations of the present species are represented by the short striae in that one. 
Locality. —Pecos village, associated with Spirifer cameratus and Terebratula subtilita. It 
occurs in the same connection at Weston, Missouri, and at other localities. 
SPIRIFER CAMERATUS.—Plate II, figs 9, 12, 13. 
Spirifer cameratus, Morton, 1836, American Journal of Science, vol. 29, p. 150, plate II, fig 3. 
Spirifer meusebachanus, Iio'emer, Texas, p. 420, 1849 ; Kreide von Texas, 1852, p. 88, plate 
XI, fig 7. 
Spirifer triplicates, Hall, Stansbury’s Report, 1852, p. 410, plate IV, fig 5. 
Shell large inflated, transverse, subtrigonal or semicircular; scarcely alate; plications numer¬ 
ous, rounded or subangular, disposed in fasciculi; dorsal valve with the sinus of moderate depth, 
becoming very broad at the base, and marked by longitudinal plications; beak acute and 
strongly incurved; area moderately large, sublinear extending to the extremities of the hinge 
line, and vertically striated; ventral valve with the mesial elevation distinct, marked by longi¬ 
tudinal plications. 
The form of this shell varies in some degree in specimens from different localities. It is in 
general somewhat inflated, and varies from trigonal to semicircular, depending on the promi¬ 
nence of the lower margin of the shell. The umbo is often very gibbous, and the heak abruptly 
incurved, but in this character there are some variations. The mesial sinus is subangular 
above, and becomes broader and gently curved towards the base. The longitudinal striae are 
° When these collections were first submitted to me in July, 1855, I suggested the name of Spiriferpilosus for this species ; 
and it having once been in print, though not published under this name, I here make the explanation. The publication of 
Dr. Shutnard’s name in December, 1855, has consequently precedence over the one proposed by me. 
