302 PROCEEDINGS OF THE \ !'/70\ 1/, MUSEUM. vol. xxxv. 



Eloedenia retifera, new species. 6 



Kloedenia scotica (JBeyrichia kloedeni, var. scotica Jones and Hull.) 



Kloedenia simplex Jones. 



Kloedenia smocki a (Beyrichia smocki Weller). 



Kloedenia sussexensis {Beyrichia sussexensis Weller). 



Kloedenia tuberculata {Beyrichia tuberculata Salter). 



Kloedenia wallpaclcensis a {Beyrichia wallpackensis Weller). 



Kloedenia wilckensiana {Beyrichia wilckensiana Jones). 



Kloedenia wilckensiana plicata {Beyrichia wilckensiana plicata Jones). 



Of the above species, A. initialis and K. prcenuntia arc middle 

 Ordovician and K. simplex late Devonian. All the others are of 

 Silurian, mainly late Silurian, age. 



Tt will be seen from this list of species that Kloedenia, as here de- 

 fined, includes only six of the twelve species and varieties which have 

 been referred to it. Most of the others constitute a distinguishable 

 group of which K. pennsylvanica Jones is a good example, and which 

 it is proposed to separate as a new genus under the name Kloedenella. 

 The new genus, as will be more fully set forth on a following page, 

 differs from true Kloedenia, as understood by the writers, chiefly in 

 the more cylindrical form of its shells and the greater inequality of 

 its valves. In both of these respects, typical KUvdcii'm is essentially 

 the same as Beyrichia, the differences between the two lying in the 

 relative convexity and lobation of the valves. 



In Beyrichia the valves are depressed convex, the three lobes are 

 represented by sharply defined ridges or elevations which rise ab- 

 ruptly above the flattened floor of the valves. The ridges are sepa- 

 rated by deep, vertical furrows, which, though varying in width, 

 are yet very constant in their length. As a rule, the posterior furrow 

 extends across the valve to the ventral rim. The anterior furrow 

 commonly is limited below by the ventral junction of the anterior 

 and median lobes, but when the latter is isolated it passes around 

 the lower side of the median lobe and merges with the posterior fur- 

 row. 



In Kloedenia the main furrows never extend across the valves, but 

 are confined t<> its dorsal half. They mark off a rather large sub- 

 median node and often converge beneath so as to isolate it. The 

 anterior and posterior lobes are broad and never ridge-like, but, 

 as a rule, form part of the general convexity of the valve. In fact, 

 the majority of the species might be described as approximately 

 uniformly convex save for the short furrows inclosing the median 



node. 



" American species. 



6 The surface ornament, practically obsolete marginal rim, the small spine aj 

 posterior extremity of hinge, ami the unusually slight depth of the sulci are 

 characters which will distinguish this species. See Plate XXXVIII, fig. 18. 



Formation and locality.- -Helderbergian, Dalhousie, New Brunswick. 



Eolotype. Cat. No. .->:;:•;;:», U.S.N.M. 



