EEMARKS ON THE FOSSIL SHELLS FROM CHILE, COLLECTED BY 

 LIEUT. GILLISS, WITH DESCRIPTIONS OF THE SPECIES. 



BY T. A. CONRAD. 



The few secondary fossils collected in Chile, that I have been lequested to determine, appear 

 to be referable to the Oolitic, although d'Orbigny has referred two of them to the Cretaceous 

 period — his Turritella Andii and Pecten alatus. Coquand and Bayle have, however, arranged 

 them in a section of the Oolitic group, which they have termed "Etaaes du Lias superieur a la 

 Gryphee arquee et de I'oolithe inferieure." They name Terebratula tetrcedra and T. ornitJwce- 

 2^Jicda, Sowerby, as South American species ; but two shells collected by Lieutenant Gilliss, 

 though closely related to the former two, appear to be distinct. The Turritella Andii of d'Or- 

 bigny is found in Europe, but its geological relations are uncertain. There remain, then, only 

 two species of Ostrea, the forms of which genus are not so satisfactorily comj^ared with Eu- 

 ropean types as in many other genera, and it is with some doubt I refer them to exotic sjiecies. 

 There is in the collection of the Academy of Natural Sciences a species of Terehratida resembling 

 T. meridioncdis, and very likely identical with that which I have described in this report. It is 

 said to have been obtained in the Andes, at the elevation of perpetual snow. None of these 

 species of South American shells have yet been found in any part of North America ; and, as 

 the continent has been so frequently crossed by exploring expeditions, it is not likely they occur. 



TEREBRATULA. 

 Platk XLI, Fig. 4. 



1. T. SUBEXCAVATA. Ovato froui base to apex, with three folds at base; sides rounded; umbo 

 not veiy prominent ; basal margin profoundly sinuou.s. 



LonilUy. Cordillera de Doiia Ana ; 13,432 feet above the ocean. 



Allied to T. jyerovaUs, Sowerby, but a very distinct species. The mesial J'old is short and 

 deep, and the lateral ones less deeply impressed. The umbo is not large, as in tlie titer idiunalis. 



, Plate XLII, Fig. 10. 



2. T. MERiDioNALis, Conrad. Ovate, both valves ventricose ; umbo prominent ; sides and 

 base rounded. 



Locality. Cordillera de Doiia Ana. 



Tliis species difi'ers from T. ovoides of Sowerby, in being broader and more obtuse at base, &c. 



Plate XLII, Fig. 8. 



3. T. suiiTETRiEDRA, Conrad. Suboval, with three prominent ribs on the mesial elevations, 

 and five or six on the sides ; ribs angular, acute. 



Loeality. I'ortezuelo de Manilas, 0,545 feet, and also on the Cordillera de Dona Ana, 13,432 

 feet, above the ocean. 



DiH'ei'S iVoni '/'. felnedra, Sow., in its less viiiti-ico.su form, uiul in having tlueo iiisfcad of i'oiir 

 or fivt' plaits on the mesial elevation, itc. 



