116 



Barrandey Logan and Hall 



Bathyunis is a new genus, and as yet has no stratigrapliical 

 value in comparisons. Those which I described as Olenus have 

 proved to be not true Oleni, and though much resembling that 

 genus, are nevertheless distinct ; I have proposed the name 

 Barrandia and Bathynotus for the two forms.* These have yet 

 no stratigraphical value, except so far as their relations to estab- 

 lished genera may aid in that direction. 



The genera D'lkelloce'phalus and Menocei:>halus are of the Pots- 

 dam group ; and so far the Quebec group is in parallelism with 

 the Potsdam and Calciferous strata. 



Of the other genera, we know Asaphus, Illcenus and Ceraurus 

 (= Cheirurus) in the Treuton limestone and Hudson River groups ; 

 lllcenus and Ceraunism the Upper Silurian strata of Niagara age, 

 or the third fauna of Barrande ; while Ceraurus occurs also in the 

 Devonian of Europe. Amphion is known in the second fauna in 

 Europe, and, doubtfully in the first. 



Ceraurus does not occur in this country, so far as I know, 

 above the Niagara group, though known in the Devonian rocks 

 of Europe. 



The following tabular arrangement of the genera found in the 

 Quebec group will serve to express more distinctly the relations 

 of the crustacean fauna of these rocks. 



The letters at the head of the columns have the same refer- 

 ences as those used in the communication of Sir Williain Losan. 



* Thirteenth Annual Report of the Regents of the University of N. Y., 

 on the State Cabinet of Natural History, Albany, December, 1860. 



