237 



Terebratula — continued. 



compressa. . dilated ; upper margin dentated, subflexuous ; beak 



produced, pointed. . Mons. 

 granulosa. . subdepressed, rounded ; upper margin rostriform, 



produced forwards ; grooves granular ; beak short. . Mount 



Marius. 

 articulus. . trigonal, depressed, delicately striated longitudinally ; 



upper margin angular, beak short. 

 radiata. . subdepressed, rounded ; contracted in the lower part, 



dilated in the upper ; radiating longitudinal grooves ; 



margin subflexuous. 

 pumila. . very small, compressed, small valve fiattish, radiated 



with longitudinal grooves, beak pointed, produced. . Maes- 



tricht. 

 spirifera. . trigonate, transversely dilated, with spiral bodies 



placed in the inside over the lower border, which is 



angular ; beak short, perforated. . Derbyshire*. 



Almost all the above English terebratiilce are contained in Mr. 

 Sowerby's elegant work on Mineral Conchology. 



* The shells possessing ihe characters here particularized form the 

 genus spirifa' of Mr. Sowerby. 



