ADDENDU M. 



A reexamination of the strata in Avery's creek and in Erie cliff, has 

 shown that the Nautilus bed does not rest directly upon the Strophalosia bed, 

 but that about seven feet of shale intervene. Recent favorable exposures in 

 Avery's creek have allowed the investigation of these beds to some extent- 

 though no complete section could be obtained. The best, for purposes of 

 measurement, though not for collecting fossils, is near the southern end of 

 Erie cliff, where the strata are apparently in place, and where the Strophalosia 

 and Nautilus beds are about seven feet apart. 



The following species have been obtained from exposures in Avery's 

 creek, just above the fall. The relation of the beds, which furnished the 

 fossils, to the Nautilus and Strophalosia beds, is only approximately given, as 

 the exposures did not admit of accurate measurements. 



(<y) Shale, one foot above Strophalosia bed. 

 Crustacea : 



1 Phacops rana. c 



Lamellibranchiata : 



36 Pterinopecten conspectus, r 

 40 Pterinea flabella. r 



Brachiopoda : 



91 Stropheodonta perplana. rc 

 99 Chonetes scitula. r 

 100 C. lepida. rc 

 105 Spirifer mucronatus. rc 

 Crinoid stems, r 



Bryozoa : 



141 Stictopora incisurata. C 



Anthozoa : 



152 Streptelasma rectum, r 

 Coral. 



