388 Systematic Paleontology 



This very variable species, of which Hall gave fourteen figures to illus- 

 trate the variation in form, has an aspect so unique that in mature ex- 

 amples it will not be confounded with any other Oriskany brachiopod. 

 In the younger stages there are two shell forms, one with a wide ventral 

 cardinal area and square shoulders and another with a pinched ventral 

 beak and rounded cardinal angles. The former, described as the variety 

 immatura on the following page, is the more common and typical expres- 

 sion of B. suessana. The latter may be confounded with R. cumherlandice 

 but a careful comparison will show that that species is more elongate and 

 pinched posteriorly, there being no cardinal angles. 



Very common throughout the Ridgely member, but more particularly 

 at about the middle of the Oriskany formation. 



Occurrence. — Oriskany Formation, Eidgely Member. Knobly 

 Mountain, Williams Road, Ridgely, and Miller's Spring near Cumberland. 

 Hancock, Maryland ; Pendleton County, West Virginia, on the north 

 fork of South Branch of the Potomac River. 



Andrews, many years ago, gathered a great quantity in fine preservation 

 from the two quarries now abandoned in the city of Cumberland. 



Collections. — Maryland Geological Survey, American Museum of 

 N"atural History. 



Renssel^^ria (Beachia) suessana var. immatura n. var. 

 Plate LXVII, Fig. 16 



Description. — Square-shouldered form with well-developed ventral false 

 cardinal area represents the main stem in R. suessana. In the Shriver 

 member it is the only form thus far seen. The young specimens found 

 in that member are decidedly square-shouldered and semicircular in out- 

 line. The exterior is smooth with strong groAvth varices and there is no 

 inflection of the margins. This same form is also shown by the early 

 growth varices of R. suessana. 



Length 1.7 cm. ; width 2 cm. 



Occurrence. — Oriskany Formation, Shriver Member. Lowest beds 

 at Cash Valley and Winchester Road near Cumberland, higher beds at 

 Pinto. 



Collection. — U. S. National Museum. 



