12 PROCEEDINGS OF THE NATIONAL MUSEUM vol. ;8 



SYSTEMATIC DESCRIPTIONS 



Class CRUSTACEA 



Superorder BRANCHIOPODA Latreille 



Order CONCHOSTRACA Sars 



Family BRADORIIDAE Matthew 



Bivalved Conchostraca equivalved or possibly slightly inequi- 

 valved, with a straight hinge line. Surface closely punctate, other- 

 wise even except for a more or less conspicuous node, the ocular 

 tubercle, located near the antero-dorsal corner (Bradoria) and of an 

 additional eminence in the median third of the length, believed to 

 be the muscle spot (Walcottella). Shell structure calcareo-corneous 

 to phosphatic. 



Genus BRADORIA Matthew 



Bradoria Matthew, Bull. Nat. Hist. Soc. New Brunswick, No. 18, 1899, p. 204; 

 Canadian Rec. Sci., vol. 8, 1902, p. 451. — Jones Geol. Mag., Dec. 4, 1902, 

 p. 402, text fig. 5. — Matthew, Geol. Surv. Canada, Rept. Cambrian Rocks 

 Cape Breton, 1903, p. 162 (genotype B scrutator Matthew). 



Bradorona Matthew, Canadian Rec. Sci., vol. 8, 1902, p. 444. — Jones, Geol. 

 Mag., Dec. 4, 1902, p. 402, text fig. 2. — Matthew, Geol. Surv. Canada, 

 Rept. Cambrian Rocks Cape Breton, 1903, p. 156 (genotype B. perspicator 

 Matthew) . 

 (Including Indiana (part), Schmidtella, and Leperditia Matthew), 



After a careful comparison of all the species referred by Matthew 

 to Bradoria, to the subgenus Bradorona, to Schmidtella and Leper- 

 ditia, and in addition a number of undescribed species in the Walcott 

 collection, we conclude there is absolutely no valid ground for either 

 generic or subgeneric distinction between the several groups. The 

 only difference between Bradoria and Bradorona is that while in the 

 former the ventral outline is rather broadly and almost uniformly 

 curved, in Bradorona it is more or less produced; hence more abruptly 

 curved medially or at some point behind the middle. In conse- 

 quence of this slight, and certainly not generic, difference, the pro- 

 portionate height of the valves is less in Bradoria than in Bradorona. 

 It is a fact, however, that even in the most typical Bradoria {B. 

 scrutator) the ventral outline is less broadly curved than presented 

 in Matthew's figures of the species; and from this we pass by such 

 gradual steps to Bradorona perspicator and B. spectator, in which 

 (of Matthew's species) the median production of the ventral outline 

 is most conspicuous, that the observer can not fail to be impressed 

 with the invalidity of the distinction. 



Regarding the species referred by Matthew to Leperditia, namely 

 L. ? rugosa and L. minor, and to Schmidtella, namely S. pervetus, S. 



