PAL^OSTOLOOY OF NEW YORK. 



CYRTOCERAS, Goldfuss. 1832. 



A glance at the following historical sketch will show the proportion of the 

 species which have already undergone changes in generic reference, and the 

 inclusion of forms in the genus Cvrtocera8 possessing the most unlike charac- 

 ters. This has arisen from the recognition of genera which have as yet no 

 recognized defined limits beyond the individual opinions of the various authors. 

 Another source of constant confusion is the poverty of the material, which, so 

 long as it continues, must render a satisfactory determination and arrangement 

 of all the species impossible. 



One cause for the uncertain and unsatisfactory reference of species, in this 

 country, during former years, has been the want of books for reference, and of 

 collections for comparison. Every author has been compelled to rely upon 

 such information as lay within his reach ; and this was often of the most 

 incomplete and fragmentary character. There existed, also, a preconceived 

 opinion, from earlier teachings, that the genus Nautilus did not exist in Palae- 

 ozoic formations ; and owing to this impression, such forms as Cyrtoceras 

 maximus, Conrad, and Gyroceras Burlingtonensis, OwEn, were referred to these 

 genera, while they have all the characteristics of genuine. Nautilus, to which 

 they are now referred. From a similar misapprehension, or preconceived 

 opinion, the generic term Lituites has been applied to forms not very dissimilar 

 from those just named, and which have all the features of true Nautilus ; 

 while others, .arranged under the same generic term, belong to the genus 

 Gvroceras, as generally accepted. 



The species here described, and indicated below, are placed provisionally 

 and with some degree of reservation under this genus. At the present time, 

 and with the information at hand, no satisfactory generic separation can be 

 made. In the following arrangement, those species preceding C. eugenium, 

 viz., C. metula, C.formosum, C. densum, C. Hector, C. liratum, C. alternatum and C. 

 morsum, form a heterogeneous group without natural interrelations, and with- 

 out any special connection with the species following. 



