21 



species. The specimens were associated with the characteristic Carbon- 

 iferous or Coal-Measure species, while the type-specimens of Meek and 

 Worthen were obtained from the Chester limestone of the Subcarbon- 

 iferous series in Illinois. 



Genus SPIRIFERINA d'Orbigny. 



SPIRIFERINA SPINOSA var. CAMPESTRIS. The collection contains 

 specimens of a species of Spiriferina from near Santa Fe, New Mexico, 

 and Camp Cotton wood, Lincoln County, Nevada, that correspond in all 

 essential respects with 8. spinosa Norwood and Pratten, except that the 

 specimens show none of the minute spines of that species. These speci- 

 mens were found associated with species that are characteristic of the 

 Upper Carboniferous period, while theirs were collected from the Chester 

 limestone of Illinois of the Subcarbouiferous series. It seems probable 

 that both this and the foregoing species survived from the Subcarbon- 

 iferous to the Upper Carboniferous period, with comparatively little 

 change. 



Genus DIELASMA King. 



DIELASMA ? BOVIDENS Morton (sp.) The species, so widely distri- 

 buted in the Carboniferous rocks of the United States, and so widely- 

 known under the names of Terebratula bovidens Morton and T. milli- 

 punctata Hall, is among the collections associated with species that are 

 its common associates elsewhere. It is found to possess comparatively 

 strong dental plates extending the lull length of the ventral beak, and 

 also a reflexed loop extending farther forward than the middle of the 

 shell. The exact details of the loop have not yet been made out ; but I 

 have at present but little doubt that the shell in question belongs to 

 genus Dielasma King. 



CONCHIFERA. 

 Genus AVIOULOPEOTEN McCoy. 



AVICULOPECTEN CoREYANA(*p. nov.) Shell moderately large; width 

 not exceeding, or a little less than, the height ; margin of the basal half 

 forming almost a true semicircle; posterior margin thence continued 

 straight and parallel with the axis of the shell about half-way to the 

 cardinal margin, then curving outward, it forms with the last-named 

 margin a somewhat acute angle. Hinge-line a little longer than the 

 full width of the shell, at right angles with its vertical axis, projecting 

 farther backward than the posterior border, but not reaching quite so 

 far forward as the anterior border. 



Left valve convex, most so in the umboual region ; beak prominent, 

 not projecting beyond the cardinal border ; posterior ear moderately 

 large, acutely angular at the outer extremity, not distinctly defined from 

 the body of the valve; anterior ear defined by a moderately deep byssal 

 sinus and a distinct depression running from it to the beak, not so prom- 

 inent as the other ; its outer border rounding downward and inward 

 from the cardinal border into the byssal sinus, where it is met by the 

 incurving anterior border of the body of the valve. 



Surface marked by numerous fine, radiating costae of unequal size, 

 whjch are in turn marked by very fine radiating stria3, all crossed by 

 fine, concentric lines of growth and occasional coarser lines of increment. 

 Upon the posterior ear, the radiating costa3 are obsolete ; but upon the 



