G. H, Girty — TJjpper Permian in Western Texas. 365 



are more abundant in the " dark Permian " than in the white 

 limestone whose fauna I am attempting to summarize. 



The brachiopod fauna is abundant, and while of an undoubted 

 Carboniferous facies, presents one which is apparently later and 

 certainly different from that of our usual Carboniferous rocks. 

 The following species were found : 



Streptorhynchus near pelargonatus Schl. 



Derbya n. sp. 



Derbya sp. 



Derbya Bennetti ? 



Meekella n. sp. 



Chonetes n. sp. near trapezoidalis Waagen 



Productus semireticulatus var. 



Productus pileolus Shum. ? 



Productus cora d'Orb. ? 



Productus near Wallacianus Derby (2 sp.) 



Spirifer Mexicanus Shum. 



Spirifer n. sp. 



Squamularia ? Guadalupensis Shum. 



Martinia n. sp. near elongata Waagen 



Ambocoelia planiconvexa? 



Spiriferina Billingsi Shum. 



Spiriferina sp. 



Spiriferina n. sp. 



Seminula n. sp. 



Hustedia? papillata Shum. 



Pugnax n. sp. 



Pugnax Swallowiana Shum. 



Camarotoechia indentata Shum. 



Camarotoechia sp. 



Dielasma near truncatum Waagen (2 sp.) 



D-ielasma ? ? sp. 



Dielasma ? n. sp. 



Hemiptychina near H. sparsiplicata Waagen 



Spirigerella ? sp. 



Lyttonia sp. 



Richthofenia (several sp. ?). 



Besides the forms listed are several new genera and species 

 of terebratuloid shells, which, even in the comparatively few 

 specimens in our collections, present a really remarkable 

 differentiation. Many of the genera cited above are new to 

 JSTorth America. Among these may be mentioned Lyttonia^ 

 Richthofenia^ Spirigerella^ and Hemiptychina^ though in one 

 case, at least, the generic reference is questionable. Many of 

 the genera common to our other North American faunas are 

 represented in part or wholly by species of peculiar types not 

 found in them. An orbicular Sjpiriferina with short hinge 

 line is one of these. 



