142* 



ADDENDA. 



PHOLADOMYA OBLITA. Tab. XII, fig. 5. 



Shell ovately ventricose, umbones large, elevated ; anterior side tumid, posterior side 

 produced, compressed, its extremity gaping with a narrow aperture; superior border 

 concave, inferior border curved elliptically ; sides of the shell with very numerous, fine 

 radiating lines, which are effaced towards the lower borders, and are absent towards the 

 two lateral extremities. 



The shell which most nearly resembles the present species is the well known 

 Pholadomya Jidicula, Sow., from which it is distinguished by the shorter and more 

 ventricose figure, by the much larger and more elevated umbones, by the considerable 

 curvature of the lower border, and by the surface, which, in lieu of the acute elevated 

 costac of P. Jidicula, has very much more numerous, fine, lines, which vanish towards the 

 lower border. Pholadomya oblita has occurred rarely in sandstone at the base of the 

 Great Oolite, and also in the Inferior Oolite of the Cotteswolds. 



Localities. Minchinhampton Common, in the Great Oolite. Selsley and Frocester hills, 

 in the Inferior Oolite. 



18* 



