250 SYSTEMATIC PALEONTOLOGY 



Superfamily STROPHOMENACEA 



Family STROPHOMENIDAE 



Genus STROPHOMENA Blainville 



STROPHOMENA STOSEI n. sp. 



Plate XXXVII, Figs. 1-4 



Description. This brachiopod, which is the most frequent fossil of 

 the few species discovered in the Frederick limestone is known from 

 both brachial and pedicle valves, although none show the hinge line 

 clearly. Its general shape is that of Strophomena sinuata James of the 

 Cincinnatian rocks, but 8. stosei differs conspicuously in the occurrence 

 of several fine radiating striae between each of the larger coarse ones. 

 The interior of the brachial valve in each of these species seems to be 

 quite alike and the reference of this new species of .Strophomena to the 

 8. sinuata group appears to be warranted. 



The specific name is in honor of George W. Stose, of the U. S. Oeo- 

 logical Survey, who helped collect the type specimens. 



Occurrence. FREDEKICK LIMESTONE. Just east of Frederick, Mary- 

 land. 



Collections. Maryland Geological Survey, U. S. National Museum. 



STROPHOMENA SCULPTURATA n. sp. 

 Plate XLIX, Fig. 1 



Description. Although this new species belongs to a group of brachio- 

 pods not uncommon in the faunas of eastern North America, all of these 

 species happen to be new, so that comparison is not necessary. It is the 

 only brachiopod in the Middle Ordovician limestone with such a highly 

 sculptured shell and for that reason will be easily recognized. Between 

 each of the very distinct radiating ridges there are five or six smaller 

 radiating striae visible only under a lens. Transverse to these radiating 

 striations are concentric, squamose ridges of growth quite similar to those 

 obtaining in Leptaena charlottae. In the latter respect the group of 

 species is related to Leptaena, but other features suggest Stropliomena. 



An average specimen is 10 mm. high and 13 mm. wide. 



