666 Systematic Paleoxtology — UrrER Devonian 



Bellekopiion clarki n. sp. 

 Plate LXVII, Figs. 17-20 



Description. — Shell subglobose : diameter of shell about equal to great- 

 est diameter of volution at aperture. Inner volutions small, gradually 

 enlarging to middle of outer volution, from which point it expands 

 rapidly to aperture. Aperture expanded ; peristome sinuate in front, 

 slightly auriculate on side. TJmbilieus small, apparently open. Surface 

 bearing a distinct dorsal carina and ornamented by regular equidistant 

 fine transverse stritY, which bend backwards in approaching carina over 

 which they pass with a marked retral curvature. 



Diameter of shell usually 8-12 mm., diameter of aperture same. 



This sjDecies approaches B. mcera in form but is much smaller and dif- 

 fers in ornamentation. It resembles B. acidUlrata. in ornamentation but 

 is more globose and has a distinct carina. It also resembles B. pelops 

 of the Onondaga in some respects. This is a common and characteristic 

 species of the Parkhead, rarely occurring in the Chemung. It is named 

 in honor of Wm. Bullock Clark, State Geologist of Maryland. 



Occurrence. — Jennings Formation, Chemung Member. Two miles 

 north of mouth of Town Creek, 1949; Town Creek, 2228. Parkhead 

 Member. Williams Eoad, on Polish Mountain, 1660 ; Town Creek, 

 1679 abundant, 1851 abundant; 4 miles south of Pratt abundant; 2 

 miles west of Pawpaw, 1493; Little Orleans; 2^2 miles above mouth of 

 Sideling Hill Creek. 



Collection. — Maryland Geological Survey. 



BeLLERPHON cf. CLARKI 



Description. — A species of Bellerphon resembling B. clarki is found in 

 the Ithaca fauna at Yellow Springs. It differs from B. clarM in possess- 

 ing faint revolving stria" and a somewhat more prominent carina. It is not 

 sufficiently perfect for illustration. 



Occurrence. — Jennings Formation, Woodmont Member, Ithaca 

 Fauna. Yellow Springs, West Virginia. 



Collection. — Marvland Geological Survey. 



