NO. 2 BRACHIOPOD SUPERFAMILY STENOSCISMATACEA GRANT II3 



Fig. 26. — Colediutn evexum n. sp., Chappel Limestone, McCulloch County, 

 Tex.; transverse sections X6, USNM 142149, original length 9.4 mm., distances 

 given from pedicle valve beak. 



A. 0.1 mm. : camarophorium begins as swelling on septum ; cardinal process 

 apparent. B. 0.3 mm. : cardinal process gone. C. 0.5 mm. D. 0.7 mm. : inter- 

 camarophorial plate, hinge plate, and dental plates all detached. E. 1.1 mm. : 

 spondylium and hinge plate gone, crura visible. F. 1.6 mm. : septum of camaro- 

 phorium detached from valve floor, intercamarophorial plate still present. Cama- 

 rophorium ends at 1.8 mm. 



spondylium and relatively long intercamarophorial plate. Some speci- 

 mens have two low and broad costae on the fold, resembling slightly 

 those of C. obesum (Clark) and C. explanatum (McChesney). How- 

 ever, on C. evexum these costae are much lower and broader, less dis- 

 tinct, and begin farther anterior; the brachial valve is much less 

 strongly convex, especially less sloping at the anterior, than in either 

 of these two other species, and the shell outline is wider and more dis- 

 tinctly pentagonal. This species occurs with C. undulatum n. sp. but 

 differs in its smaller size, less transverse outline, less convex brachial 



Table 21. — Measurements of Coledium evexum from the Chappel Limestone of 



Central Texas 



Measurements, in millimeters 



