FOSSIL SHELLS. 283 



OSTEEA, Linn. 

 Plate XLII, Fig. 9. 



1. O. IRREGULARIS. Eliomboidal ; lamelloso; striate concentrically; superior valve flat; 

 inferior valve irregular, ventricose, sessile at the umbo or whole surface ; sides ascending, 

 subrugose. 



Locality. Cordillera de Doiia Ana. 



0. irregularis, Munster, Gold. Petrif. vol. 11, p. 20 to 79, Fig. 5. 



Plate XLI, Fig. 1. 



2. 0. GREGARiA. Elliptical, encurved ; inferior valve acutely carinated, affixed ; superior 

 valve plano-convex, folds simple, narrow, bifurcate. 



Locality. Cordillera de DoHa Ana, 13,432 feet above the ocean. 



0. gregaria, Sow. Gold. Petrif. vol. II, p. 7, PL cxxiv, Figs. 1, 2. 



PECTEN? 

 Plate XLI, Fig. 2- 



P. ALATUS. Inequilateral ; anterior side of the larger valve considerably enlarged towards 

 the base in form of a wing; ribs, fourteen, rounded below, flattened above ; umbo very promi- 

 nent ; upper valve flat, a little excavated in the middle ; ears small. 



Locality. Cerro de Tres Cruces, in the province of Coquimbo, and 2,887 feet above the sea. 



F. alatus, (Von Buch,) D'Orbigny, Petrif. rec. in Amer. par Humb. p. 3, Fig. 1 — 4. 



This shell probably belongs to the genus Neithea of Drouet. D'Orbigny remarks that it 

 forms entire mountains, and that Humboldt observed it in immense quantities at the height of 

 8,400 feet between Guambos and Montan, on the route from the river Amazon towards Lima. 



LITHOTKOCHUS, Conrad. 

 Plate XLI, Fig. 3. 



Conical or trochiform ; aperture contracted, subquadrate, entire ; labrum not extending be- 

 yond the line of the body whorl above. 



L. Andii. Conical ; whorls six (?) ; sides straight, oblique, carinated near the base, and 

 angulated ; whorls marked with conspicuous revolving lines ; angle of the body whorl obtuse 

 or rounded. 



Localities. Coquimbo ; San Felipe, Peru ; near Hamburg. 



Turritelli Andii, D'Orbigny, Voy. dans Amer. p. 104, PL vi. Fig. 11. 



Pluerotomaria Eumholdtii, De Buch. Petri, rec. en Amer. par Humb. Fig. 26. 



TrocMis Struveamus, Zim. Dunk. Palajont, p. 185, t. 26, Fig. 2. 

 This shell has been referred to two or three different genera, but it does not correspond in 

 characters with any of them. I have no doubt of its being an extinct genus. Perhaps Turri- 

 tella Benauxiana, d'Orbigny, a Cretaceous species, should be associated with it. Dunker's 

 Troclms Struvianus was found among tertiary fossils, and he is in doubt whether it was out of 

 place or not. It is most likely a stray Jurassic species ; and, if so, is no doubt identical with 

 the South American shell. 



