Maryland Geological Survey 327 



rectly made out the interior characters of the Russian Upper Carbonif- 

 erous shell, the basis of Fischer de Waldheim's genus Orthothetes, all sub- 

 sequent writers, until 1904, have followed him in his conclusions. In 

 that year, however, Girty showed that the Russian type had the char- 

 acters for which Waagen proposed the genus Derbya in 1884, and accord- 

 ing to the law of priority in publication, all the so-called Derbyas must 

 be referred to Orthothetes, which should be spelled Orthotetes. This ref- 

 erence left the brachiopods referred to the last-named genus by authors 

 except Waldhcim without a group name. For these Girty has proposed 

 Schuchertella, with Streptorhijnchus lens White as the type. 



SCHUCHERTELLA PROLIFICA n. Sp. 



Plate LX, Figs. 1-3 



Description. — This abundant and medium-sized shell for this genus has 

 the general form of Schuchertella rvoohvorihana, but differs from it in 

 many ways. The valves are thinner and less convex, the ventral cardinal 

 area narrower, and the striae far more abundant. In 8. woolworthana 

 the striae are abruptly elevated and there are from nine to thirteen in 5 

 mm., while in S. prolifica they are lower and have from thirteen to twenty 

 in the same space. In the latter species the striae are also crossed by ex- 

 ceedingly delicate concentric lines of growth, which are not so well pre- 

 served in the other form. In the interior of S. prolifica the muscle scars 

 are not impressed and are therefore but rarely seen, while the cardinal 

 process is less strongly developed than in S. woolworthana. There 

 are transitional forms, however, which unite this species so closely with S. 

 woolworthana of the Coeymans as to make their separation often difficult 

 or even arbitrary. 



Length about 2.6 cm. ; width about 3.3 cm. 



Occurrence. — Helderberg Formatiok, Keyser Member. Keyser, 

 West Virginia ; Dawson, Devil's Backbone, Corriganville, Tonoloway, 

 Maryland. 



Collections. — Maryland Geological Survey, IT. S. National Museum. 



