of the Rocky Mountains. 73 
Lingula prima, Conrad. 
Our specimens are generally more or less exfoliated, but as 
near as can be determined, they ia to wie with the well 
known New York species in every ite abundant in 
the Primordial sandstone of the Black ype In ise. 44°, lon. 104°. 
Lingula antiqua, Hall. 
ee oe amongst our specimens several varieties of forms, 
much more elongated and more attenuate towards 
the t oer than others. Some of the latter agree quite nearly 
with Dr. Owen’s figures of Lingula pinnaformis, which is gene- 
rally regarded as a vari iety of L. antiqua (though it may be dis- 
tinct) while others are in ng respects like the typical forms of 
. antigua from New 
Locality — Black Hills — Big Horn Mountains. 
Obolelia nana, Meek and Hayden, Proc. Acad. Nat. Sci. Phila., Dec. 1861. 
The genus Obolella has been recently established by Mr. Bil- 
lings, the able Paleeontologist of Canadian 1 4, 5. 
ogica It ry of a grou h\ 
small shells allied to Obo to Obolus of E dhwald, ‘Sat 
presents fundamental pba in the form 
and arrangement of its muscular impressions. 
The A of the genus is clonal allied to the 
fo figured, though specifically distinct. 
The figures here given are enlarged threé diameters. No.1, , 
Tepresents the outside of the dorsal ree 
and No. 1, }, the inside of the aut 
valve, showing the muscular sears. The 
“== and the es of the valve 
© radiating striz represented on the eitolaged portion of fig. 
2,4, are too numerous and crowded in the cut. 
—_ oe gregarea, (M. and H.) Proc. Acad. Nat. Sci. Philad. 
nis species resembles in form Pugiunculus striatulus of Bar- 
tande (Neues Jahrb., pl. 9,) but differs in being very much , 
er, and much more convex on the ventral side, as well , 7 
5H =e being destitute of striw. This little shell must have 
ted in yast numbers, since on a single slab not more 
than six by eight inches kes we adi counted nearly two 
hundred individuals, Occ uivalent to the Potsdam 
hearin aoe the New Souk rac ae ae Big Horn Mountains, 
1072: 
Ax. Jour. igesibed Series, Vou. XXXIII, No. 97.—Jan., 1862. 
10 
