MADE BY DR. ANTONIO RAIMONDI IN PERU. - 283 



and smaller towards the base; posterior to the beaks are traces of very faint radi- 

 ating lines, more closely placed than the concentric ribs and barely perceptible 

 except in the interspaces. 



Figure. Natural size. 



Locality. From the Pueblo of Pion, in the department of the Amazons. Two 

 isolated specimens without associates, considered Cretaceous by Dr. Raimondi. 



Remarks. This shell can be distinguished by the rounded gaping posterior end 

 and gently dilated margins, as well as by the marked concentric ornamentation. 

 It is from a hard white limestone unlike any other rock among the upwards of 

 400 specimens in the collection. 



CORBULA, Brng. , . 



C, sp. indet. 



Numerous casts of a small equivalve shell, doubtless of this genus, occur among 

 the Cretaceous fossils of the neighborhood of Ollon. Beyond the fact that they 

 are nearly equilateral and equivalve (a slightly greater convexity existing in the 

 right valve and the characteristic biangularity posteriorly), they show no characters. 

 I therefore do not feel warranted in naming the species, since no good diagnostic 

 characters can be given from the material. 



C. NUCULOiDES, n. s., PI. 40, fig. 10. 



Shell small, nearly equivalve ; beaks very slightly in advance of the middle ; 

 anterior end elongately rounded, base regularly curved ; posterior cardinal margin 

 concave, the surface flattened; posterior end produced, narrow and rounded. Sur- 

 face marked by fine lines of growth. 



Locality. From the coal mine of Pariatamba. Lias. 



Remarks. From the other two species, with which it is associated, this shell 

 can be distinguished by its form, resembling a Nuculana, and by its surface, nearly 

 devoid of the heavy lines so characteristic of its genus. 



C. Peruana, n. s., PI. 40, fig. 11. 



Shell small, very inequilateral; beaks placed in advance of the middle; anterior 

 end sloping convexly above and most prominent near the base ; base broadly and 

 slightly convex ; margin abruptly bent down ; posterior side excavated behind the 

 beaks, a concave area running to the posterior end and bounded by a sharp angle ; 

 posterior end narrow and produced. Surface marked by small concentric ribs. 



Locality. With the preceding. 



Retnarks. A very characteristic Corbula, recognizable from even a fragment 

 both by its outline and markings. It differs from the preceding by its more cunei- 



