330 PHOCEEDINGS OF THE NATIONAL MUSEUM. vol. xxviii. 



OBOLUS (LINGULELLA) ISSE, new species. 



Ill form and size this .shell recalls 0. {L.) jxxjonlpensii^; it differs 

 from it ill the form of the dorsal valve and the eharacter of the outer 

 surface. The shell is rather strong- and made up of several thin layers 

 or lamelUe. Its outer surface is marked hy concentric lines of growth, 

 sometimes grouped in more or less elevated bands, and over all there 

 is a thin encrusting or scabrous layer that has a minutely granular, 

 dull surface, somewhat like that of O. {L/tujnh'pis) gregwa but very 

 much finer in its granulations or [loints. The inner layers of the shell 

 are dark, shin}", and marked by concentric lines of growth and radiat- 

 ing striae 



Forrnatlon and localitij. — Middle Cambrian. Near Cave Spring, 

 Fish Creek Range, Utah. 



OBOLUS (LINGULELLA) ORUS, new species. 



This is a shell of the (). (Z.) iiumtlcaluti form, ))ut difi'ers from it in 

 beiii'^- more elongate; ventral valve more acuminate and dorsal valve 

 proportionall}' larger. Its nearest allies in form are among the group 

 of narrow, elongate shells occurring across the continent at (^ape 

 Breton. It difi'ers from all of them 0. (Z.) coUicia^ O. {L.)fiuiiiensis.^ 

 0. (Z.) caniw^^ etc: in having a thick, strong shell and usually more 

 acuminate dorsal valve. Tlie exterior surface bears ratlier strong 

 concentric lines of growth, and very fine, irregular, undulating, ele- 

 vated strise that suggest the surface of O. ( Westonia) eUa^ when seen 

 in a reflected light with a strong magnifier. 



This little shell occurs al)undantl' , l)ut good interiors have not been 

 found. The main vascular sinuses appear to lie submarginal in both 

 valves, and the visceral area of the dorsal valve narrow, extending a 

 little beyond the centre of the valve. 



Formation and local !ty. — Middle Cambrian. Limestones of the 

 Reagan formation, interliedded in the middle part of the Reagan green- 

 sand, 15 miles north of Fort Sill, one-half mile east of Canyon Creek, 

 Wichita Mountains, Oklahoma Territory. 



OBOLUS (LINGULELLA) PELIAS, new species. 



This shell most nearly resembles O. (Z.) deHideratun. It differs in the 

 squareness of the dorsal valve caused by the slightly curved sides and 

 cardinal slopes. The ventral valve suggests the broader forms of 

 O. (Z.) desiderat us, and the dorsal valve those of 0. (Z.) /nosla and O. 

 (Z.) ir'mona of the St. C^roix sandstone. 



The outer surface of the shell is marked by clearly defined con- 

 centric lines that are slightly irregular, and narrow, fine radiating 

 undulations or costa? toward the frontal margins. When unusually 

 well preserved, the surface also shows very fine, irregular concentric 



