Troimdoi-eptus Fauna at Canandaigua Lakk, N. \. 155 



Cystodicta incisuraia, 

 Tceniopora exigua, 

 CainaroUvchia horsfordi, 

 Atrypa reticularis, 

 Cyrtina hamiltonensis, 

 Spirifer audaciiliis, 

 S. viucro7iatus, 

 A^nboccelia timbonata, 

 Reticularia fimhriaia, 

 Nucleospira conciuna, 

 Athyris spiriferoides, 

 Craniella hamiltonicE, 

 Stropheodonta incequistriata . 



S. perplaiia, 



S. iowaensis, 



Orihotetes ilioiuingeusis 



atiis, 

 Chonetes coronatus, 

 C. scitulus, 



Proditctella spiuiilicosfa, 

 RJupidoviella vamixoiii, 

 K. pen elope, 

 Cypricardi/iia identa, 

 DiapJiorostoma lineata , 

 Phacflps raiia. 



arc fist ri- 



Dalinaiiites boofhi. 



All of these species are common in any Hamilton section and range 

 from top to bottom. A comparison of almost any three large faunules 

 would show a good part of this list in common, so that it is hardly 

 safe to correlate the zones on such evidence. The abundance of Cys- 

 todicta in all these may be explained by local conditions which favored 

 the development of large numbers of colonies. 



The twelve species which are most common at Canandaigua Lake 

 in this faunule are as follows, their relative abundance being in the 

 order named : 



Chonetes initcronatus, 



Clionetes coronatus, 



Ort/u)t/ietes cliemungensis arcti- 



striatus, 

 Phacflps rana, 

 Tentaculites bellulus. 



Chonetes sciticlus, 

 Pholidops hamiltonicr, 

 Tropidoleptus carinatus, 

 Spirifer mucronatus, 

 Strophdonta inaequistriata , 

 Cystodicta incisurata. 

 Tceniopora exigua 



For a comparision with this list, the dominant range frequency lists 

 prepared by Williams^ from a study of the Eighteen Mile Creek and 

 Cayuga Lake sections and the distributional frequency list for eastern 

 New York may be taken, for although these lists do not represent 

 exactly the most common fossils, they are a close approximation. 



For a further comparison there has been prepared, following Wil- 

 liam's method, a dominant range frequency list from the Thedford 

 section as reported by Shinier and Grabau,- and it stands as follows : 



•H. S. Williams, liull. U. S. Geol. Survey, 210, 1903. 



2 " The Thedford Section," Bull. Geol. Soc. Am., vol. 13, pp. 149-1S6, 1902. 



