14 Cincinnati Society of Natural History. 



West Union bed, at the quarry in the southeastern part of 

 West Union, Ohio. 



Coarser specimens, with several phcations in the sinus, 

 and with rather strong and distant concentric striations, in 

 the Osgood bed of Indiana, are more nearly related to Atrypa 

 calvini, Nettelroth, from the Louisville limestone in the vicin- 

 ity of Louisville, Kentucky. Atrypa marginalis, as identified 

 from the Brownsport formation of western Tennessee, belongs 

 to the same group. 



Spirifer radiatus, Sozcerby. 

 Plate II, Fig. 8. 



An internal cast of the pedicel valve of a nonpl'cate form 

 of Spirifer^ with a rather quadrate outline posteriorly, and 

 with a distinctly defined median sinus. Length 15 mm., width 

 19 mm. Dental plates continuing for 5 mm. from the beak. 

 Apparently a trace of a median septum. 



West Union bed, at the blufif northwest of Martins, in 

 Lewis county, Kentucky. 



Spirifer radiatus-obsoletus, var. nov. 

 Plate II, Figs. 10 A, B, C. 



Spirifer belonging to the group typified by Spirifer radia- 

 tus, differing chiefly in the nearly complete obsolescence of the 

 median sinus and fold. In a specimen 22 mm. in length, 48 

 mm. in width, and 17 mm. in thickness, the sinus is indicated 

 only by a slight flattening of the anterior part of the pedicel 

 valve, while the fold is represented by a broad but only slightly 

 elevated median part which is not distinctly limited laterally, 

 as in Spirifer radiatus. However, there are specimens from 

 the same locality in which there is a narrower slightly elevated 

 median part with a distinct lateral boundary. These speci- 

 mens evidently indicate the ^lose relationship of this form to 

 typical Spirifer radiatus. The interior of the pedicel valve 

 exhibits two dental lamellae extending from 8 to 10 mm. 

 anterior to the beak, and also a low acute median septal ridge 



14 



