No. 186.J 63 



O^T^LOaXJE 



OP THE 



SPECIES OF FOSSILS, 



DESCRIBED IN VOLUMES I., II. AND III. OF THE PALAEONTOLOGY OF NEW-TOEK J 

 With the Corrections in Nomenclature, as far as determined to the present time. 



At the time of the publication of the first volume of the Palseonto- 

 logy of New- York, many of the species were referred to genera 

 already described, in preference to proposing new genera, even where 

 the identification was not entirely satisfactory : first, in deference 

 mainly to European authors, from whom we had derived our know- 

 ledge of the palaeozoic fossils of parallel or equivalent strata; and, 

 secondly, because the materials available were not always in a con- 

 dition to furnish satisfactory evidence, from the interior of the shell, 

 of the relations of the fossils under examination. With few excep- 

 tions beyond the Brachiopoda, all the determinations of species were 

 made from external characters; and I was even compelled, in a few 

 instances, to describe new genera, with only a knowledge of the 

 exterior of the shells. The collections at my disposal w^ere very 

 inadequate to the production of a satisfactory work; and it was only 

 from the necessity arising from my position, that the volume was 

 published before more complete investigations had been made. 



At that time no general studies of the Brachiopoda had been 

 made, or, if made, had not been published; and generic names had 

 been adopted by authors without scrutinizing the relations of the 

 fossils grouped under them. The terebratuloid forms had been proved 

 not to be true Terebratulse, and the generic name Atrypa of Dalman 

 had been adopted, but without restriction; so that it finally came to 

 include a heterogeneous assemblage of species similar to that before, 

 and to some extent still, designated as Terebrahda. 



Although American authors favored the adoption of Rafinesque's 

 genus Strophomena^ European authors were not inclined to the same 

 opinion; and Dalman's genus LeptcEna was at that time regarded by 

 several eminent European palaeontologists as more clearly defined, 

 and better applicable to a large number of forms, than the un- 



