CO^CHYU A— DITHYRA. 20. 59 



Shell oval or oblong, equi valve, inequilateral, mostly closed. 

 Hinge witli two teeth in each valve, and a cavity between 

 them : lateral teeth none. Ligament internal. 



In this genus there is a vacant space in both the valves be- 

 tween the teeth, causing them to be rather remote from each 

 other. One of the teeth is generally concave or inclining to 

 spoon-shaped. 



We have dedicated it to the memory of Montagu, whose pre- 

 mature death all lovers of this interesting science must sincerely 

 lament. 



MoNTAcoTA testa ovatd, costis longitudinalibus obsoletis. substriau. 



Shell oval, with obscure longitudinal ribs. 



Tab. nost. 1 1, fig. 9 and 10. 

 Ligula substriata. Montagu, Test. Suppl. p. 25. 



Pennant, Brit. Zool. iv. p. 169. 

 Mya substriata. Dillwyn, Descript. Catal. p. 47. 



Wood, Conch, p. 102. 



Tnrton, Conch. Diet. p. 10-3. 

 Mus. nost. Abundantly on the spines of the Echinus purpureus, 

 io which they are attached by slender filaments issuing from 

 the middle of the margin. 



"» 



The detection of this singular habitat we owe to the researches 

 of our young conchological friend, Mr. Edw. Harington. 



Shell the eighth of an inch long, and a little more in breadth, 

 oval, convex, sliglitly contracted in the middle, white or yellow- 

 ish white and semitransparent, with obscure and rather remote 



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