„ , OSTRACODA.. '691 



Krausella.l 



Family BEECHERELLIDiE. 

 Genus. KRAUSELLA, n. gen. 



Carapace small (1.5 to 2.5 ram. in length), somewhat elongate, subelliptical, 

 obscurely triangular or semiovate in outline, the dorsal margin more convex than 

 the ventral, the latter straight or but gently convex; with moderately thick and 

 very unequal valves; right valve the smaller, drawn out posteriorly into a strong 

 spine-like process; left valve overlapping the right all around. 



Type: Krausella incequalis, n. sp. 



At present I am acquainted with only four species that should be placed in 

 this genus, viz.: the two about to be described, Bairdia anticostiensis Jones (Quart. 

 Jour. Geol. Soc, vol. xlvi, p. 548; 1890) from the Hudson River or Cincinnati forma- 

 tion of the island of Anticosti, and an undescribed form (near K. arcuata) which is 

 rarely met with in the upper beds of the same formation in Ohio and Indiana. These 

 species do not agree with Bairdia since the spine-like process is not formed by the 

 tapering ends of hoth valves, but is restricted to the right valve, the left valve being 

 rounded posteriorly and resembling the corresponding valve of a thick-shelled 

 Bythocypris. We have therefore the difference that while the two valves of a Bairdia 

 are similar in outline, they are quite different posteriorly in Krausella. 



The spine-like process reminds of some of the species placed by the author under 

 his genus Beecherella* If there is any true relationship between Krausella and 

 Beecherella, and I confess that I am strongly inclined to believe there is, then the 

 Beecherellas were probably all described and figured in a reversed position. Another 

 thing that has become more evident than formerly is that more than one generic 

 type has been included under Beecherella. Considering the strongly marked peculi- 

 arities of the type species, B. carinata, it seems probable that we shall eventually 

 find it desirable to restrict the genus to it. 



Of B. suUumida we know only the right valve, and this is exceedingly like the 

 same valve of Krausella arcuata. Still, I hesitate to say that it should be referred to 

 the present genus since it may be shown that it, like B. cristata, has the posterior 

 spine on the overlapping instead of the smaller valve. In the last species namely, 

 the right valve seems to overlap the left, though the overlap is very slight and 

 scarcely distinguishable. Should the relations of the valves (with respect to 

 overlap) in these two species prove to be really the reverse of what we know to 

 be the case in Krausella, a distinct generic grouping for them would probably be 

 justifiable. 



* American Geologist, vol. vlii, pp. 197-204, pi. 2, Oototer, 1891. In this paper the author descrlhes the new genus Beecher- 

 ella, with six new species and one variety, all derived from the Lower Helderherg strata of New York, 



