70 Bui^LETiN 4 184 



both cardinal and lateral teeth well developed; right valve with 

 one strong and one rudimentary anterior lateral and one strong 

 and one rudimentarj^ posterior lateral — all short, one cardinal 

 tooth; left valve with two tooth-like projections fitting over both 

 strong anterior and posterior laterals, and two cardinal teeth; 

 ligament external, extending from the umbo to near the posterior 

 lateral teeth; muscular scars as shown in the figure; inside of the 

 valves coarselj^ punctate. 



Localities. — Alabama: i mi. N. of Midway. 



Georgia: Base of Midway, Chattahoochee river; 

 soft layer of gray, micaceous clay with casts of 

 large Turritella moj'toni, not far north of the 

 mouth of Sandy creek, Chattahoochee river. 



GASTROCH^NA. 



Gastroch^na gainesensis n. sp., PI. 6, figs. 12, a. 



Specific characterization. — General form as indicated by the 

 figures, though the posterior is represented as somewhat too nar- 

 row since the posterior-dorsal margin is broken away; size one-half 

 that represented in the figures; shell extremely gibbous anteriorly, 

 with a great anterior-basal opening; main face of shell somewhat 

 more coarsely striate than anterior portion, i. e., that in front of 

 a vaguely defined line of flexture by no means as distinct as in 

 Martesia; found as is common for this genus surrounded by a 

 globular or pear-shaped incrustation. 



Locality. — Georgia: Uppermost layers of the Midway lime- 

 stone as exposed on Chattahoochee river at Ft. 

 Gaines. 



Type. — Paleontological Musfeum, Cornell Univ. 



Gastrochcsiia ciniitariopsis i\. sp. , PL 6, fig. 13. 



Specific characterizatio7i. — General form as indicated by the 

 figure; figure twice natural size; marked exteriorly by a few 

 concentric undulations; a strong ridge extending from the umbo 

 to the posterior-basal margin, posterior to the same the shell is 

 nearly flat, with a trace of a radiating sinus; anterior-basal mar- 

 gin widely gaping; surrounded by an elongate globular covering 

 like other members of the genus. Rare. 



Locality. — Georgia: Uppermost bed of the Midway limestone 

 as seen on Chattahoochee river at Ft. Gaines. 



Type. — Paleontological Museum, Cornell Univ. 



