136 vox IHERIXG — MOLLUSCAX FAUNA OF PATAGOXIA. [Aprils, 



the concentric ribs indicate a relationship to the genus Inoceratnus, 

 from which however it is distinguished by the short and broad liga- 

 mental area and the well-developed auricles of the dorsal margin. 

 I regard the species therefore as the representative of a new genus, 

 of which I offer the following diagnosis. 



Neoinoceramus, gen. nov. 



Genus Aviculidarum testa sequivalvi, oblique-ovata, biauriculata, 

 concentrice costata, cardine recto, crasso brevi oblique-sulcato. 



I believe this genus to be nearly allied to Inoceramus, the species 

 of which are exclusively Mesozoic. Although, because of the 

 incomplete preservation of the specimen described, the systematic 

 position of the genus is not definitely fixed, there can be no doubt 

 that this species represents one of the most remarkable discoveries 

 of Mr. Carlos Ameghino's later expeditions. 



I have much pleasure in dedicating this exceedingly interesting 

 species to my friend Dr. Florentine Ameghino, not only in appre- 

 ciation of his excellent palseontological work, but also as an 

 acknowledgment of the liberality with which he has confided to me 

 the study of the invertebrates of his collection, permitting the types 

 to remain in the Museu Paulista, which for this reason possesses the 

 finest existing collection of Patagonian invertebrates. Of these two 

 new species, one is the first representative of the Cephalopoda from 

 the Tertiary of Patagonia, the other is a new type of Pelecypoda, 

 nearly allied to the Mesozoic genus Inocera?nus. The collection is 

 also rich in Corals and Echinoderms ; among the latter, the study 

 of which I have entrusted to Mr. Loriol le Fort, are also Crinoidea. 



With reference to the paper of Mr. Hatcher, I have examined 

 the question of the significance of the Patagonian and Suprapato- 

 gonian beds, which Mr. Hatcher regards as only different facies of 

 a single formation. The fact that some species are common to both 

 horizons and that the number of such common species increases 

 with the progress of investigation, induced me for a time to agree 

 with Mr. Hatcher's opinion. It was therefore of importance for me 

 to reexamine the question with reference to the new material, 

 which was not derived from Santa Cruz, but from northern Pata- 

 gonia. The result was not favorable to Mr. Hatcher's views. This 

 may be seen from my paper on " The History of the Argentine 



