364 Systematic Paleoktology 



lines corresponding to the sharp interlocking edges of the front and 

 lateral margins of the valves. These fine striae doubtless represent lines 

 of growth, which have become wholly obsolete on other parts of the shell." 

 Hall, 1857. 



Length 2 cm. ; width 2.4 cm. 



Occurrence. — Helderberg Formation, New Scotland Member. 

 Devil's Backbone, Maryland ; Cedar Cliff, West Virginia. Becraft Mem- 

 ber. North Mountain. 



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



Uncinulus globulus n. sp. 

 Plate LXIV, Figs. 13-15 



Rhynchonella nucleolata Hall 1857 (in part), Tenth Ann. Rept. N. Y. State 



Cab. Nat. Hist, p. 68. 

 Rhynchonella nucleolata Hall, 1859 (in part), Nat. Hist. N. Y., Pal., vol. ill, 



p. 227, pi. xxxi, figs, la-lc (not the many other figures which are U. 



nucleolatus) . 



Description. — Hall in describing R. nucleolata the second time figured 

 many specimens, a few of which do not pertain to the species intended to 

 bear this name. In regard to these he wrote : " It is possible that the 

 figs, la, b, c of pi. xxxi are distinct from those which follow." It is this 

 globular form that is found in Maryland and none of the larger sub- 

 triangular (in section) shells are associated. This fact has led the writer 

 to take out of U. nucleolatus these rotund forms and apply to them the 

 name globulus. 



Length and width about 10 mm. 



This rhynchonelloid is easily distinguished from all associated species 

 by its globular form and the shallow, narrow, thrice plicated ventral sinus; 

 from U. mutabilis, to which it is most closely related, by the globular form 

 and the less abundant plications. Thus far no undoubted specimens of 

 the latter species have been seen from Maryland. 



Occurrence. — Helderberg Formation, New Scotland Member. 

 Corriganville, Devil's Backbone. 



Collection. — Maryland Cieological Survey. 



