no. 1646. REVISION OF BEYRICHIIDJE— ULRICH AND BAS8LER. 3X7 



now quite clear that such a course would be unwarrantable. Taking 

 into account only this, that both have two constant and similarly 

 placed nodes, the logical course would be to unite them. But if the 

 apparently unquestionable derivation of II. radiata from the 

 Devonian species of Hollina is considered, the impropriety of the sug- 

 gested reference cannot be ignored. Ulrichia is one of the Primi- 

 tiidee; Hollina is a derivitive — presumably somewhat atavistic — of 

 Beyrichiidse. 



As is evident from several preceding references in the paper to 

 Hollina^ the writers now regard the resemblance of certain species 

 to Ctenobolbina, and of others to Bollia, as atavistic stages in the 

 Devonian and Mississippian evolution of the typical Beyrichian 

 stock, and not as survivals of the generic types to which they were 

 originally referred. Ulrich placed most of the Devonian species 

 under Ctenobolbina because of their general similarity in form, loca- 

 tion, and range of variation to the C. subcrassa group of that genus, 

 while the later //. granifera was referred to Bollia solely because the 

 ventral union of its two nodes forms a loop precisely like the inner 

 loop of typical species of that genus. In neither case were the char- 

 acters now relied on, such as the two constant rounded nodes and 

 the broad frill on the posterior and ventral margins, taken into ac- 

 count, and the genetic relations to Beyrichia, though suspected, were 

 not appreciated as they should have been. "Loops" strikingly like 

 that in Bollia occur in other types. This was recognized by Ulrich 

 in 1894 " in discussing Drepanella bigeneris, a notable instance of 

 this kind. 



Subfamily KLOi^DElNELLINJE. 

 Genus KLCEDENELLA, new. 



Beyrichia (part) Jones and Authors. 

 Kloedenia (part) .Tones. Ulbich, and most Authors. 



Bollia? (part) Ulrich, Geol. and Nat. Hist. Surv. Minnesota, Final Rept., 

 III. Pt. 2. 1S«. 14, p. 669. 



Carapace small, strongly convex, elongate, somewhat barrel-shaped, 

 the length usually less than 1.5 mm.; dorsal edge nearly straight, ven- 

 tral edge usually somewhat concave, ends approximately equal in 

 height but differing in outline, the antero-dorsal angle often rectan- 

 gular and always more distinct than the post-dorsal. Valves un- 

 equal, the right overlapping the left around the ends and the ventral 

 side. Of the lobation, the constant features are two sharply im- 

 pressed vertical or slightly oblique furrows, separated by a narrow 

 lobe, in the posterior half. In the more simple forms, these furrows 

 extend only about half across the valve. Anterior half may be uni- 

 formly convex, but, as a rule, is more or less clearly bisected vertically 

 by a straight or curved furrow! When present, this anterior furrow 



Geol. and Nat. Hist. Surv. Minnesota, Final Rept., Ill, Pt. 2, 1S94, p. 671. 



