LOWER CARBONIFEROUS FOSSILS. 537 



The only dorsal valve observed is that figured. It is nearly flat at 

 first, and geniculate, with well-marked, somewhat pointed ears. 



The material from the Yellowstone National Park seems to be identical 

 with the form identified, described, and figured by White as Productus parvus 

 (loc. cit.). 



Compared with Meek and Worthen's figures of that species, P. parvi- 

 formis is seen to be uniformly smaller, narrower in proportion to the width, 

 more deeply arched, and more elongate. It seems like a miniature form of 

 P. gcdlatinensis, with which I have at one locality found it associated, and 

 of which, although no intermediate forms have been observed, I am almost 

 disposed to regard it as a variety. 



Formation and locality: Madison limestone, Crowfoot Ridge, Gallatin 

 Range, top of bed 25 ; J. P. Iddings and Gr. M. Wright, Same, bed 30, bed 

 31 ; J. P. Iddings and W. H. Weed. South of Forellen Peak, Teton Range; 

 S. L. Penfield. Mountain Spring, Nevada. 



CAMAROPHORIA King, 1846. 



Camarophoria ringens Swallow. 



PI. LXIX, figs. Iff, lb, lc. 



Rhynchonella ringens Swallow, I860 : Trans. St. Louis Acad. Sci., Vol. I, p. 653. Keyes, 



1895: Geol. Surv. Missouri, Vol. V, Pt. II, p. 102. 

 Camarophoria ringens Hall aud Clarke, 1893: Pal. New York, Vol. VIII, Pt. II, p. 214. 

 Rhynchonella (sp.) Keyes, 1895 : Geol. Surv. Missouri, Vol. I, Pt. II, PI. XLI, figs. 8, 11. 



There is a little doubt that the form under discussion is identical with 

 that described by Swallow under the name Rhynchonella ringens. His was 

 a large shell (length, 1.90 inches; breadth, 1.43 inches; thickness, 0.99 

 inch), triangular in outline, marked by about fourteen large plications, 

 eight of which were in a broad shallow sinus. More recently Keyes (loc. 

 cit.) cites the species and says there are twelve plications. 



The material from the Yellowstone National Park is scanty. Shell 

 large, acuminate-ovate. Dorsal valve flat on top, bending abruptly at the 

 sides and at the front. Ventral valve shallow. Beak long, sharp, not much 

 incurved, apparently pierced by a triangular or oval foramen, without 

 deltidial covering. The surface is marked by twelve or fourteen large 

 but somewhat lax, rounded plications, two or three of which on the 

 lateral slopes are not very distinct. Two or three plications are on the fold, 



