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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I48 



Fig. 20. — Coledium erugatum n. sp., Moorefield Formation, Okla., USNM 

 142125. Longitudinal section near midline, X5, showing profiles of one edge of 

 camarophorium and posterior part of its septum, hinge plate, one edge of spondy- 

 lium, and part of septum of spondylium. 



&<&&> 



B 



TTT 



V. ' 



H 



I 



K 



Fig. 21. — Coledium erugatum n. sp., Moorefield Formation, Okla., USNM 

 142127, transverse sections, X6, length originally 11.4 mm., distances given from 

 pedicle valve beak. 



A. 1.2 mm.: hint of cardinal process. B. 1.5 mm.: hinge plate and cardinal 

 process. C. 2.1 mm. : cardinal process large, fimbriate. D. 2.6 mm. : no cardinal 

 process. E. 2.9 mm. F. 3.0 mm. : hinge plate reduced, spondylium low, narrow. 

 G. 3.4 mm. : intercamarophorial plate low, spondylium absent, septum low. H. 

 4.0 mm. : intercamarophorial plate nearly gone. I. 4.2 mm. J. 4.7 mm. : cama- 

 rophorium high, wider, flexed; septum thin: section cuts anterior edge. K. 5.5 

 mm. : camarophorium high, strongly flexed transversely, septum detached from 

 valve floor. All structures absent anterior to 5.7 mm. from beak. 



