BRACHIOPODA—PROTREMATA. 



215 



75. S. (Leptostrophia) beckei Hall. (Fig. 256.) Devonic. 

 Pedicle valve very depressed convex, with small beak. Brachial 



valve nearly flat. Surface marked with strong, close, bifurcating 

 strise which are crossed by fine concentric lines and by more or 

 less regular concentric wrinkles. In its surface characters it thus 

 much resembles Leptcena rhomboidalis but differs in being almost 

 flat. 



Helderbergian of New York, Kennedy Channel of the Arctic 

 region. 



76. S. (Leptostrophia) magnifica Hall. (Fig. 257I) Devonic. 

 Very large, with rounded hinge extremities. Pedicle valve 



depressed convex at the umbo; brachial valve slightly concave. 



Fig. 257. Stropheodonta {Leptostrophia') magnifica, pedicle valve partly removed 

 and showing impressions of inner structures ; interior of brachial valve.. 



Radiating strise rather faint and regularly bifurcating two or three 

 times. 



Oriskany of New York, Maryland, Ontario. 



77. S. magniventer Hall. Devonic. 

 Length usually % the breadth. Pedicle valve convex in the 



umbonal region with slightly incurved beak. Hinge line some- 

 times extended. Radiating striae regular and slightly elevated. 

 Oriskany of New York, Ontario, Quebec. 



78. S. patersoni Hall. (Fig. 258.) Devonic. 

 Convex. Distinguished by its form, the pedicle valve being 



gibbous just in the middle and somewhat deeply deflected at the 



