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TEREBRATULA resupinata. 

 TAB. CCCXXV. 



Spec. Char. Transversely ovate, longitudi- 

 nally striated ; stria? minute, numerous, and 

 equal ; imperforate valve most convex. 



Syn. Conch. Anomites resupinatus. Martin 

 Pet. Derh. tab. 49. /. 13 and 14. 



Length about two-thirds the width : the hinge line is 

 not very long, but it is straight, and accompanied by 

 two nearly flat surfaces, perpendicular to each other, 

 between it and the beaks ; that beneath the prominent 

 beak of the flatter valve has a triangular foramen in the 

 middle of it. The little ridges between the striae are 

 often interrupted by punctums that appear to be the 

 bases of slender depressed spines : the middle of the 

 more convex valve is slightly concave. 



I have met with several hollow specimens of this shell, 

 but have seen no vestige of a spiral cartilage in any ; 

 nor does it appear that either of the beaks has a circular 

 perforation. The form of the hinge strongly resembles 

 that of the genus Spirifer, but is not incompatible with 

 that of Terebratula, with which at present this species 

 must remain. 



Not very rare in the Mountain Limestone of Derby- 

 shire. 



