322 DESCRIPTION OF A COLLECTION OF FOSSILS, 



P. alatus, Bayle & Coq., M. G. Soc. Fr., 2 s., v. 4, p. 14, PI. 5, f. 1-2. 



Id. Con., U. S. AstroD. Exped., p. 283, PI. 41, f. 2. 

 Janira id., Rem., Pal. Chile, p. 18. 

 Neithea id., G., Syn. Cret., p. 147. From Colombia to Chile. 



The age of this fossil has been the cause of great difference of opinion. Dr. Raimondi calls 

 his specimens Jurassic, with some doubt. D'Orbigny places it in the Neocomien, while others 

 carry it as low as the Lias. If it is older than Cretaceous it is the only species of the genus 

 that is found outside of the limits of that formation. My own opinion is that it is somewhat 

 high in the Cretaceous ; not only from the fact that the genus is eminently characteristic of tlie 

 chalk and green sand ; but because all of the other fossils, sent with it by Humboldt and Degen- 

 hardt from Colombia to Von Buch, as well as the additional species collected by Dr. Gibbon and 

 described by Dr. Lea, and, again the third collection, described from the same region by Forbes, 

 all seem to belong to the age of the white chalk, or not far below it. 

 Neithea quinqxjecostata, Sby. (sp.). 

 Pecten id., Sby., M. Con., PI. 56, 



Janira id., d'Orb., P. Fr., T. Cret., p. 632, PI. 444, f. 1-5. 

 Neithea id., Gabb, Syn. Cret., 1861, p. 148. 



Id. Gabb, present paper. Cret.; Peru. 



Lima raricosta, Bayle & Coq., M. G. S. Fr., 2 s., v. 4, p. 26, PI. 6, f. 3-4. Jur.; Chile. 



L. {Plagiostoma) truncatifrons, B. & C, loc. cit., p. 25, PI. 6, f. 5. 



Id. Hup., Gay's Chile, p. 296. Jur.; Chile. 



L. (P.) DtiBiA, Hup., Gay, p. 297, PI. 9, f. 5. Jur.; Chile. 



Plicatula RAPA, B. & C, M. G. S. Fr., 2 s. V. 4, p. 16, PL 5, f. 8-10. 



Id. Hup., Gay, p. 293. Jur.; Chile. 



P. TORTA, Gabb, new sp. Cret.; Peru. 



Anomia parva, Gabb, Proc. Phil. Acad., 1860, p. 198, PL 3, f. 15. Cret. ; Chile. 



A. Peruana, Gabb, new sp. Cret.; Peru. 



Placunanomia lima, Gabb, new sp. Cret. ; Peru. 



OSTREA ABRUPTA, d'Orb., A. Mer., p. 93, PL 21, f. 4-6. Cret. ; Col. 



O. (Exogyra"?) Atacamensis, Phil., Atacama, p. 145, PL 1, f. 11-12. Jur.? Chile. 



O. CALLACTA, Con., Proc. Acad. N. S., PhiL, 18t5, p. 139, PL 22, f. 1. 

 0. sp. indet., Dana, Wilkes' Exped., PL 15, f. 1. 



0. callacta, Gabb, present paper. Jii'- > Pei'u. 



O. ENCARPiFERA, Hup., Gay's Chile, p. 286. Jur.; Chile. 



O. GREGARiA, Sby., M. Con., PL 111, f. 1-3. 



Id. Bayle & Coq., M. G. S. Fr. 2 s., v. 4, p. 24. 



Id. Hup., Gay's Chile, p. 285. 



Id. Con., U. S. Astron. Exped., p. 28.3, PL4],f. 1. Jur.; Chile. 



O. INOCERAMOIDES, d'Orb., A. Mer., p. 94. Cret. ; Col. 



O. LARViFORMis, Gabb, new sp. Cret. ; Peru. 



0. Marshii, Sby., M. Con., PL 48. 



Id. B. & Coq., M. G. Soc. Fr , p. 24, PL 5, f. 3. 



Id. Hup., Gay's Chile, p. 284. Jur.; Chile. 



