WHITE.] PALEONTOLOGY CRETACEOUS FOSSILS. 293 



behind the anterior extremity ; posterior unibonal slopes quite prominent 

 or subangular, and continued obhquely to the posterior basal angle, so as 

 to dixidc the surface of each valve into two nearly equal, elongated, in- 

 equilateral triangles, the lower of which forms the concave flanks ; an- 

 terior muscular scar small, but very deep ; posterior muscular scar larger, 

 shallow, suboval ; palhal Une not distinctly seen, but apparently with a 

 small sinus. Surface with rather coarse, irregular marks of growth. 



" Length, 1.15 inches ; height, 0.55 inch ; convexity, 0.58 inch. 



'•'■ Locality ami position. — The sijecimeu was given to Dr. Hayden at 

 the Salt Lake, and was found in that region, but he could not ascertain 

 the precise locality. It is almost certainly Cretaceous." 



There were three examples of this species found among the collec- 

 tions formerly in ]\Ir. Meek's hands for investigation, of one of which 

 two views are given on j)late x. ]!!s^othing fiu-ther has been learned as 

 to their true locality and position. Neither has anythmg further been 

 learned concerning the hinge or internal characters of the shell, but it is 

 probably correctly referred to Trafpeziiim. 



Trapezium? incRONEiMA Meek. 



Plato X, fig. 5 a. 



Trapezium micronema Meek, 1873, An. Rep. U. S. Geol. Siirv. Terr, for 1872, p. 493. 



" Shell attaining a rather large size, elongate-trapeziform, the length 

 being a httle more than twice the height, which is about one-third greater 

 than the convexity; anterior margin very short and round; posterior 

 margin obhquely truncated above and narrowly rounded below ; base 

 nearly straight, or faintly sinuous along the middle, rounding uj) rather 

 abrui)tly at each end ; dorsal margin long, straight, and parallel to the 

 base; beaks depressed nearly or quite to the horizon of the dorsal mar- 

 gin, and located one-sixth the entire length of the valves from the ante- 

 rior margin; umbonal slopes prominently rounded from the beaks ob- 

 liquelj' backward and downward nearly to the posterior basal extremity, 

 while below this convexity a shallow concavity extends from each beak 

 obliquely backwai'd to near the middle of the basal margin. Surface 

 with numerous very fine, regular, crowded, thread-hke radiating lines. 



"Length, 2.28 inches; height, 1.21 inches ; convexity, 0.90 inch. 



"I know nothing of the hinge of this shell and merely place it in the 

 genus Trapezium from external characters. Its form and smface mark- 

 ings, however, are such as to leave little room for doubts in regard to its 

 relations to that genus or GoraUiophaga. 



" Locality and position. — Cretaceous coal-bearing sandstones at Bear 

 Eiver City, on Sulphur Creek, Wyoming." 



No other than the tj'pe-speciinen of this species has yet been discov- 

 ered, and consequently nothing fiu-ther is known of its characters. 



Baroda WYOMmaENSis Meek. 



Plato X, figs. 3 a and h. 



Tapes wijomivgens'ts Meek, 1871, Au. Rep. U. S. Geol. Siu-v. Terr, for 1870, p. 310. 

 Baroda tcyovtinriciisis Meek, 1873, An. Rep. U. S. Geol. Surv. Ten-, for 1872, p. 493. 



The following is Mr. Meek's original description of this species, only a 

 single specimen of which has been discovered among the coUectious 

 examined bj^ him, but that is evidently his tyi)e and only example. It 

 is figui'cd on i)late x. 



