MOLLUSCA OF LOWER CANADA. 99 



LAMELLIBRANGHIATA. 

 UNIONIDJE. 



Unio radiatus, Lamarck. Abundant in the rivers and lakes 

 of Canada East. The U. siliquoideus is often taken for this shell. 



Unio siliquoideus, Barnes. Equally common with the above. 

 For details of difference between the former species and this, see 

 Conrad's Monograph of the genus Unio. As many able concho- 

 logists deny that this is the Unio luteolus of Lamarck. I have 

 preferred keeping the name given to the species by Barnes. 



Unio Canadensis, Lea. St. Helen's Isl and, Montreal ; appar- 

 ently very rare. Some rayed specimens of a Unio which I took at 

 Quebec may be a dwarf form of this species. A single dead 

 typical specimen on the beach of the Island of Orleans : J. F. W. 



Unio cardium, Rafmesque. (U. ventricosus, Barnes.) St. 

 Lawrence ; very fine near Quebec. Unio subovatus, Lea, appears 

 to be the male of this species ; and U. occidens, Lea, a variety of 

 the female. 



Unio complanatus, Solander. By far the commonest Unio in 

 the district ; living (according to Mr. Bell) as far down the St. 

 Lawrence as Berthier below Quebec. 



Unio dilatatus, Rafmesque. (U. gibbosus, Barnes.) Widely 

 distributed in the St. Lawrence and its tributaries, but scarce.. 

 Some varieties closely resemble the last species. 



Unio rectus, Lamarck. St. Lawrence at Quebec and Montreal., 

 but somewhat rare. 



Unio alasmodontinus, Barnes, (U. pressus, Lea.) Rare : 

 L'Assomption river : M. de V. River St. Pierre, and Lachine canal 

 near Montreal : R. J. F. Rideau canal near Ottawa city : E. B. 



Unio alatus, Say. Ottawa river, near Ottawa : mouth of 

 River Rouge : R. B. 



Unio olivarius, Rafinesque. (U. ellipsis, Lea, fide J.G. Anthony.) 

 St. Lawrence at Quebec and Montreal ; fine and not infrequent at 

 Quebec. 



Margaritana margaritif 'era, Linn. (Alasmodon arcuatus.Barnes.) 

 Very large and fine in the St. Charles river near Quebec : J. F.W 

 Green and Rimouski rivers; both of the Matapedia lakes; 

 Lake St. John : R. B. 



Margaritana costata, Rafinesque. (Alasmodon rugosa, Barnes.) 

 Sparingly in the St. Lawrence about Montreal. Yamaska river 

 near St. Hyacinthe : J. F. W. 



