CONCUYUX—DITHYRA. 8. 33 



Shell reaching to two inches and a half long, and four or five 

 broad : and is distinguished from the last species, by the anterior 

 end tapering to a rounded point, and by the tooth having a small 

 projection or denticle on one side. 



Mya testa ovatd, latere anfico rotundato refleaeo, dente fasti- ovaiis. 



giato flexuoso. 

 Shell oval, rounded and reflected at the anterior end, with the 



tooth flattened at the top and flexuous. 



Tab. nost. 8, fig. 1 and 2. 

 3Ius. nost. Dublin bay, at Clontarf. 



Shell three quarters of an inch long, and an inch and a half 

 broad, convex, yellowish-white, thin, striate transversely, obtusely 

 rounded at the anterior end, where the valves reflect a little : 

 hinge near the middle ; with the tooth of the left valve truncate 

 at top, running in a straight line, the anterior extremity curving 

 inwards, and tlie hinder extremity outwards, and without addi- 

 tional denticle. 



The specimen represented in our plate, was dug up at Clontarf, 

 a few days previous to our leaving Ireland, It has the convexity 

 of the Mya truncata, with the rounded anterior end of the Mya 

 arenaria, but not so much produced. The tootli is also very 

 different from either of them. 



