12e. Left side of male paratype shell, U.S.N.M. 132484 



12f. Left side of paratype female shell, U.S.N.M. 132485 

 13. Eocytheropteron cf. tumidum Alexander, lower member of Atkinson 

 Formation, Sun Oil Company's No. 1 Johnson well, Columbia County, 

 Florida, 2,955-2,965 feet, x 45. 

 Left side of shell, U.'S.N.M. 132486 

 14a, b. Eocytheropteron semiconstrictum ? Alexander, lower member of Atkin- 

 son Formation, Magnolia Petroleum Company's No. 5B State Block 

 1A well, Franklin County, Florida, 5,138-5,144 feet, x 43. 



14a. Right side of a shell, U.S.N.M. 132495 



14b. Ventral view, U.S.N.M. 132532 

 15a-c. Orthonotacy there delicatula Swain and Brown, n. sp., beds of Washita 

 age, Odom water well No. T-l, Northampton County, North Carolina, 

 190-195 feet (15a) ; Caledonia Prison Farm water well No. T-4, Hali- 

 fax County, North Carolina, 166-171 feet (15b) and 286-291 feet 

 (15c), x 45. 



15a. Left side of holotype shell, U.S.N.M. 132496 



15b. Right side of paratype shell, U.S.N.M. 132497 



15c. Dorsal view of paratype, U.S.N.M. 132498 

 16a-c. Centrocythere annitlopapillata Swain and Brown, n. sp., lower member of 

 Atkinson Formation, Humble Oil and Refining Company's No. 1 

 Bennett and Langdale well, Echols County, Georgia, 3,700-3,710 feet, 

 x 43. 



16a. Left side of holotype shell, U.S.N.M. 132499 



160. Ventral view of paratype, U.S.N.M. 132500 



16c. Interior of paratype left valve, U.S.N.M. 132501 



50 



