608 PROCEEDINGS OF THE NATIONAL MUSEUM. 



OBOLUS iLINGULELLA) WELLERI, new species. 



General form elongate ovate, with the ventral valve subacimiinate 

 and the dorsal valve sulielliptical. Owing* to the more or less crushed 

 condition of all the specimens the exact convexity of the entire valve 

 is unknown. Surface of the shell marked by numerous elevated con- 

 centric lines of growth and very fine, slightly irregular, interstitial 

 concentric stria\ 



When the outer surface is exfoliated the inner layers show line 

 radiating stria? and concentric lines of growth. Nothing is known of 

 the interior surface of the shell. The shell 'appears to have been rel- 

 atively thin and formed of several layers or lamella\ 



A ventral valve 14 mm. in length has a width of 9 mm., and a 

 dorsal valve 1(» mm. in length has a width of 7i mm. In both valves 

 the width is slighth^ increased by the flattening of the shell. 



Ohi<er vat Ions. — This species occurs in association with O. {Lhigulejns) 

 acwnlnatus in an arenaceous magnesian limestone. It differs from 

 described species in the elliptical form of the dorsal valve and the 

 strongly filose concentric stria? of the outer surface. The specitic 

 name is given in honor of Prof. Stuart Weller, who discovered the 

 locality. The specimens representing the species were collected by 

 Mr. Henry Dickhaut. 



Formation and locality. — Upper Cambrian, magnesian limestones, 

 O'Donnell & ]\Ic^Ianiman's quarry. Newton. New Jerse}'. 



OBOLUS (LINGULELLA) CONCINNUS Matthew. 



IJnguleUa roncimm Matthew, Bull. Nat. Hist. Soo. New Brunswick, IV, 1900, 



p. 273, pi. V, tigs. 2a-b. 

 Oholm (Lingnlella) bellns ^VALCor^, Proc. U. 8. Nat. Mus., XXIII, 1901, p. 685. 



General form ovate, with the ventral valve subacuminate and the 

 dorsal valve broadly ovate. There is considerable variation in the 

 outlines of the valves. The convexity of the valves is fairly strong, 

 although they are usually more or less flattened and compressed in the 

 arenaceous shale. 



Surface of the shell is marked by fine concentric strii« and lines 

 and ridges of growth. When the outer surface is exfoliated numer- 

 ous fine radiating strife occur in the inner layers or lamellfB. The 

 inner surface is marked b}^ concentric lines of growth. In some 

 specimens scattered minute pits occur that are sometimes arranged in 

 the cast like beads along the lines of growth. The shell is of moder- 

 ate thickness and formed of a thin outer layer and several inner la}'- 

 ers or lamella^ that are slightly oblique to the outer la\'er. In the 

 older shells the oblique lamella? form laminated ridges of growth. 

 Some of the larger ventral valves have a length of 10 to 12 mm., but 

 the average length is a])out s mm. 



