376 Procccdiiif/s of the Ohio Sfiitr .Icadeniy of Sciciwc. 



1805. Spirifera {Martiiiia) coiitrarla. Wliitficld, Geol. Surv. Ohio, Vol. 

 VII, p. 471, pi. il, figs. 17-lM. 

 Maxvillc limestone: Ohio. 

 1909. Martijiia glabra var. contracta. Grabaii and Shimer, X. A. Index 

 Foss., p. 841. 

 Chester: Illinois, Ohio and Xevada. 



Description. — Shell of medium and of larger than mediiun 

 size, fairly rohust, l^roadly ovate in general otitline. 



A'entral valve rohtist. witli incm-ved Ijeak. Hinge line short, 

 equal to half the width of the shell. Area small, divifled hy a 

 rather large triangular perlicle opening. Median sinus shallow, 

 narrow, and indistinct on the heak. hut gradually increasing in 

 width toward the anterior end where it is somewhat extended 

 into the fold of the opposite valve. 



Fig. 1<'. — Martinia contracta. 



a. — Dorsal view of the type specimen from the Chester Hmestone 



of Illinois, 

 b and c. — Dorsal and profile views of a Maxville specimen. (.A.fter 



Whitfield.) 



Brachial valve less convex and nearly circidar in outline, 

 with minute heak. Median fold developed only in the anterior 

 half toward which margin it increases in size. 



Surface marked h}- very minute radiating plications, which 

 alternate in size and wliich are cn^ssed 1)_\- still finer concentric 

 lines. 



Length 14-33 nim. ; width 14-40 mm. 



The shell is characterized Iw its rohust form and hy the 

 minute radiating ])lications and the finer concentric lines. Frag- 



