ART. 4 CAMBRIAN CONCHOSTRACA — ULRICH AND BASSLER 19 



Occurrence. — Lower Cambrian (Etcheminian, El6, E26): Dugald 

 Brook, Cape Breton. (Walcott locality 10/j.) Occurs also at localities 

 lOy and nt. 



Cotypes— Cat. No. 50544, U.S.N.M. 



BRADORIA MEDIAUS, new species 



Plate 3, Figure 5 



This is another apparently imdescribed species. Its relations seem 

 to be near B. benepuncta and the new variety of B, robusta — in fact, 

 its systematic position is thought to be between these two species. 



Occurrence. — Lower Cambrian (Etcheminian, E26); Dugald Brook, 

 Cape Breton, Nova Scotia, (Walcott loc. lOp.) 



Holotype.— Cat. No. 50548 U.S.N.M. 



BRADORIA ACUTA (Matthew) 



Plate 1, Figure 25; Plate 3, Figures 1, 2 



Schmidtella acuta Matthew, Bull. Nat. Hist. Soc. New Brunswick, No. 18, 1899, 

 p. 206, pi. 4, figs. 4a-4c; Canadian Record Sci., vol. 8, 1902, p. 465, pi. 11, 

 figs. 12a-12c; Geol. Surv. Canada, Rept. Cambrian Rocks Cape Breton, 1903, 

 p. 173, pi. 13, figs. 12a-12c. 



Bradorona observator mut. ligata Matthew (part) Canadian Record Sci., vol. 8, 

 1902, p. 451; Geol. Surv. Canada, Rept. Cambrian Rocks Cape Breton. 1903, 

 p. 162. 

 Not Bradorona spectator acuta Matthew { = Bradoria subquadrata, new name). 



The types of Schmidtella acuta and type specimen B of Bradorona 

 observator ligata are unquestionably the same. As mentioned in notes 

 on Bradoria scrutator, the figured type of the supposed mutation 

 ligata (specimen A), is clearly distinct from specimen B, but can not 

 be distinguished from typical specimens of B. scrutator. Concerning 

 the types of S. acuta, there can be no doubt that Matthew^ mistook 

 the nearly vertical and almost straight posterior margin for the dorsal 

 edge. In two of his types (A and B), one or both of which were used 

 by him in illustrating the supposed Schmidtella, the small yet sharply 

 defined ocular tubercle is clearly visible near the narrow anterior 

 extremity. This feature, as well as the very finely and closely 

 punctate surface and a narrow marginal rim, is better preserved in 

 specimens belonging to the Walcott collection. Basing our judgment 

 upon all these specimens, we are satisfied that the species is a good 

 Bradoria, related on the one side to B. scrutator and B. benepuncta, 

 and on the other to B. subquadrata { = B. spectator acuta Matthew). 

 At present it is the smallest species of the genus and is distinguished 

 further by its narrow anterior end and decidedly triangular outUne 

 and from most others by its distinct though narrow marginal rim. 



