1854.] 163 



19. T. livid a Lee. Journ. Acad. Nat. Sc. 2d ser. 1,71. Tritoma livideu 

 Lacord. Erotyl. 227. I have never seen this species. 



Erotylus Fabr. 



1. E. Boisduvalii Lacord. Erotyl. 466. A large number of this specie! 

 were collected by Mr. Fendler, near Santa Fe, in New Mexico. 



2. E. californicus Lacord. Erotyl. 467. Unknown to me; said to be 

 from Southern California. 



The Committee on Messrs. Evans and Shumard's papers, read June 

 20th and August 1st, 1854, reported in favor of publication in the Pro- 

 ceedings. 



Descriptions of new fossil species from the Cretaceous Formation of Sage Creek, 

 Nebraska, collected by the North Pacific Railroad Expedition, under Gov. 

 J. Ji Stevens. 



By John Evans, M. D., a*nd B. F. Shumard, M. D. 



Avictda triangularis. (Nov. sp.) 



Shell small, thin, sub-ovate, length and breadth nearly equal, anterior ex- 

 tremity pointed, expanding rapidly towards the posterior extremity, which is 

 rounded below the wing; wing small, triangular; umbones inflated; beaks 

 pointed and nearly terminal, hinge margin with a well defined furrow running its 

 entire length ; surface with rounded, concentric slightly elevated ribs, crossed 

 by indistinct, radiating striae. 



Locality. Cretaceous formation, Sage Creek, Nebraska. The pearly nacre is 

 finely preserved in all the specimens of this shell that we have seen, forming an 

 elegant contrast with the dark hue of the matrix. 



Avicula lingua for mis. (Nov. sp.) 



Syn. Avicula undet. Owen, Final Rep. Geol. Iowa, Wisconsin and 



Minnesota, tab. vii. fig. 10. 



Shell very oblique, elongated, linguaeform, moderately convex ; surface smooth; 

 cardinal line straight, about equal to the greatest width of the shell ; posterior 

 wing triangular, acute, anterior wing triangular, separated from the body of the 

 shell, by the continuation of a shallow groove which surrounds its most gibbous 

 portion ; posterior edge sigmoid, forming an obtuse angle with the cardinal mar- 

 gin; anterior and basal edges convex ; beaks pointed, projecting a little above 

 the cardinal border, situated about one-fourth the length of cardinal line from the 

 anterior extremity. The mould of the shell exhibits a line of small tubercles, 

 commencing at the point of the beak and extending in a curve to the base of the 

 posterior muscular impression ; the latter is very large and somewhat reniform. 



Length one inch, width at cardinal border 10 lines, length from extremity of 

 anterior wing to posterior inferior extremity 19 lines. 



This species is rather common in the septaria of the cretaceous group at Sage 

 Creek, Nebraska, but perfect specimens are procured with diificulty. 



Solaritim flexistriatum. (Nov. sp.) 



Shell small, discoidal, depressed, convex, terminating exteriorly in a sharp 

 cutting edge ; velutions four or five ; spire very slightly elevated, inner edge of 

 volutions bounded by a row of tubercles ; surface marked by fine revolving thread- 

 like striae, which are crossed by fin< fiexuous striae, giving an exceedingly 

 neat reticulated appearance to th shell. Umbilicus large ; mouth sub-quad- 

 rangular. 



Dimensions. Width, 3i lines ; height, 1J lines. 



This pretty shell occurs quite abundantly in septaria of the cretaceous forma- 

 tion of Sage Creek, Nebraska. 



