60 COLORADO FORMATION AND ITS INVERTEBRATE FAUNA, [bull. 106. 



area small ; margins on eacli side of the area sometimes faintly marked by 

 line crenulations along the groove for the reception of the edge of the 

 upper valve; surface marked by about three or four rather regular plica- 

 tions on each side of the larger mesial fold or carina; lines of growth 

 obscure; muscular scar transversely oval, moderately distinct; upper 

 valve unknown. 



" Length from the beak to the opposite extremity, 1.16 inches; antero- 

 posterior diameter, about 1 inch ; convexity or depth of the under valve, 

 0.G5 inch. 



"This is a very peculiar shell, and can not be confounded with any 

 other species with which I am acquainted. Its large, prominent, me- 

 sial fold, extending from near the beak of the under valve to the 

 opposite extremity, with three or four smaller plications on each side, 

 give it much the appearance of some of the plicated brachiopoda when 

 viewed on the under side. The folds, or plications, vary somewhat on 

 different specimens; but usually they are remarkably uniform for a 

 species of this genus, and impart to the free margin opposite the beak 

 a zigzag character, very similar to the front of some species of Spirifer. 

 No specimens of the upper valve were obtained ; but it will probably be 

 found to have a large mesial sinus corresponding to the elevation of the 

 other valve, and must possess a projection, curving down at the middle 

 of the free margin opposite the beaks, to fill the deep notch in the mar- 

 gin of the other valve. 



" Thinking this species might be identical with one or the other 

 of two peculiar oysters described by Dr. Shumard, from the Cretaceous 

 rocks of Texas, under the names 0. bellaplicata and O. quadriplicata, I 

 sent him sketches of our shell, and he wrote that it is most nearly like 

 his 0. bellaplicata, though he thinks clearly distinct. The 0. bellapli- 

 cata attains a much larger size, some of the specimens being as much as 

 3 inches in indiameter, while its hinge-line is proportionally much 

 longer, and its surface distinctly ornamented with concentric markings." 



Locality and position. — Near the base of the Colorado shales at Pagosa 

 springs, Colorado, where it is associated with Ostrea lugubris, Inocera- 

 mus labiatus (=L problematicus), and I.fragilis. 



Genus GRYPPL33A Lamarck. 

 Gryph^ea newberryi n. sp. 

 PI. v, Figs. 1-5. 



Gryphaa pitckeri White, 1876, U. S. Geog. and Geol. Sur. west 100th meridian, vol. 



iv, p. 171, PI. 17, Figs. la-f. 

 Gryplum pitcltai Newberry and Meek, 1876, in Macomb's Expl. Exped. from Santa Fe" 



to Junct. of Grand and Green rivers. 

 Not Gryphcea pitcheri Morton, 1834, Synopsis Org. Rem. Cret. Group, p. 55, PI. 15, 



Fig. 9. 



The following is a copy of Dr. White's description and comments: 

 " Shell reaching a moderately large size, very variable in shape, gen- 



