TRENTON CONGLOMERATE OP RYSEDORPH HILL 65 



more practical to emphasize the difference, and to recognize the 

 form by a separate term. 



Horizon and locality. Upper Utica shale, Green Island, near 

 Albany N. Y. 



BRONTEUS GoldfllSS 



Bronteus lunatus Billings. Geol. sur. Can. rep't progress. 



1853-56. p. 338 



PI. 4, fig. 10, 11 



A single cranidium from the black limestone, which proves 

 to belong to the only species of Bronteus yet found in the 

 North American Lower Siluric, viz Bronteus lunatue 

 Billings. The character of the species, which is said by Billings 

 to be not infrequent in the Trenton limestone of Ottaw^a, but 

 which hitherto has not been represented in the state of New 

 York, was fully elucidated by Billings, and its relations to the 

 subdivisions of Bronteus commented on by Dr Clarke, who 

 reports it from the Trenton limestone near Spriflgvalley and 

 Wykoff, Minn. Lately the species has also been reported from 

 the Trenton of the far northwest (Birch island, Kinwow bay, 

 Lake Winnipeg) by J. E. Whiteaves.^ 



The species is said to posseiss all the characteristic features of 

 a typical Bronteus, but, as pointed out by Clarke, it possesses 

 only six pygidial ribs^ while by far the greater number of species 

 of Bronteus possess seven, and it agrees in this regard with the 

 two species known from the corresponding lower Siluric beds of 

 Europe, viz B. 1 a t i c a u d a Wahlenberg and B. hibernicus 

 Portlock. 



B. 1 u n a t u s Billings is thus far only known from the Trenton 

 limestone and according to Billings restricted to it. 



Horizon and locality. Black compact limestone pebble with 

 Tretaspis, Ampyx, etc. from the Rysedorph hill conglomerate. 

 (Group 5) 



1 Pal. foss, 1897. v. 3, pt 3, p. 235. 



