108 TRANS. OF THE ACAD. OF SCIENCE. 



Descriptions of Neio Palceozoic Fossils. 

 By B. F. Shumakd, M.D. 



[May, 1862.] 

 Spirifera Organensis, n. sp. 



Shell of medium size, semielliptical, very transverse, width 

 about double the length; thickness somewhat more than 

 half the length ; hinge line extended and terminating in 

 acute points : lateral margins very gently arched from the 

 cardinal angle to the front, which is excavated at the mesial 

 elevation. Ventral valve gently and regularly convex ; sinus 

 moderately excavated, gradually increasing in width to the 

 front, and marked with seven or eight small, rounded costze, 

 of which the median one is simple, while the others are de- 

 rived from the trichotomizing of two which originate one on 

 each side of the beak ; area narrow, slightly concave, termin- 

 ating at the extremities in very acute angles; deltoid open- 

 ing rather large, and forming almost an equilateral triangle ; 

 beak small, moderately elevated, and overhanging that of the 

 opposite valve. Dorsal valve less convex than the ventral, 

 flattened on each side of the mesial elevation, which latter is 

 but little elevated, rounded, expands rapidly towards the 

 front, and is limited by curvilinear margins. Surface marked 

 with small, rounded costoe, of which those on the sides bifur- 

 cate near the cardinal edge, and thence usually continue 

 without further division to the front margin, where, in the 

 specimens before us, we can count from '20-22 on each side 

 of the mesial fold and sinus; those which originate at the 

 beak are disposed in two fasciculi of three or four costse 

 each ; the surface is also covered with extremely fine waved 

 lines of growth. 



Dimensions. — Length, .95 inch ; width, 2.10 inches. 



This species is quite unlike any species known to me from 

 American strata. In general form and appearance it resem- 

 bles Spir. Forbesii (Nor. & Prat.), a fossil of the Encrinital 

 Limestone of Iowa and Missouri, but may at once be distin- 

 guished from that species by the absence of granulse on the 

 surface, and its wider deltidial opening. Compared with 

 Spir. camerata (Mort.), our shell is much more extended at 

 the hinge line, much less gibbous, and the costre are not dis- 

 posed in fasciculi as in that species. 



Geol. Pos. & Loc. — This line species was found in consider- 

 able abundance, by Dr. G. G. Shutnard, in the Coal Measures 

 of the Oregon Mountains, not far from Ft. Filmore, New 

 Mexico, where it occurs with Fusulina gibbosa, of Meek and 

 Harden. 



