866 NEW YORK STATE MUSEUM 



comparable in many respects to the present condition of the 

 Red sea, receiving comparatively little fresh-water drainage 

 with its exit to the ocean body constricted, and its shore lines 

 dotted with coral reefs, on which flourished in immense pro- 

 fusion a great variety of forms of invertebrate organic life. 



Memoir on the fauna of the Naples beds. In the 16th annual 

 report of the state geologist, I published an account of the 

 Cephalopoda of the Naples fauna, in which the great abund- 

 ance of heretofore undescribed species was made known. Next 

 in interest to the cephalopod element of this fauna come the 

 lamellibranchs, and of these nearly 70 species are now described 

 in the memoir in hand, together with such species of gastropod 

 and other mollusca as appear in the fauna. 



This remarkable contribution of new facts is by no means the 

 sole justification for the presentation of the Naples fauna. It 

 is well recognized that this organic congeries, known as the 

 fauna of Manticoceras intumescens, is one of the 

 most persistent and widespread of the zones of organic life 

 known in geologic history. Its affiliations with other manifesta- 

 tions of this zone have been pointed out in a general way by 

 the writer on other occasions, but this presentation affords the 

 first opportunity for a close analysis of the elements of the 

 fauna and their comparison with their manifestations in other 

 countries. These investigations have led further to a clear con- 

 ception of the conditions under which the fauna flourished and 

 of its relations to contemporaneous faunas within the State of 

 New York, so that we are now able to derive a definite idea of 

 the diversity of the geographic provinces which existed during 

 Portage time. Of these we have frequently spoken, recognizing 

 the fact that the Naples fauna or the western fauna of the 

 Portage time was an invader from the west, but till now we 

 have not seen clearly that this western or Naples fauna is 

 itself divided into two geographic elements, one of which pene- 

 trated farther east than the other. So that in Portage time 

 we find that the eastern part of the State was occupied by a 

 brackish or estuarine fauna represented by the Oneonta beds, 

 the central region by the autochthonic Ithaca fauna derived 

 from its immediate predecessor on the ground, the Hamilton 

 fauna, while the western province, which we have termed the 



