1865.] DAWSON — POST-PLIOCENE DEPOSITS. 87 



* Escbara elegantula, D'Orbigny. 



* Celleporaria surcularis, Packard. 



* Myriozoum subgracile, D'Orbigny. 



* Heteroporella radiata ? 



* Alecto. 



* Membranipora Lacroixii, Busk. 



BRACHIOPODA. 



Rhynchonella psittacea, Gm. 



* Terebratella Labradorensis, Sow. 



LAMELLIBRANCHIATA. 



Pecten Islandicus, Chemn. 



Leda truncata, Brown, and vars. siliqua and sulcifera. 

 *L. tenuisulcata, Couthouy, (pernula, Wood). 

 L. minuta, Mull, (caudata, Don.). 



* L. limatula, Say. 



Nucula tenuis, Mont., (var. expansa). 



* Modiolaria discors, Linn. 

 M. nigra, Gray. 

 Mytilus edulis, Linn. 



* Cardium Dawsoni, Stirapson. 



* Astarte compressa, Mont. (A. Banksii, Leach). 

 A. Laurentiana, Lyell. 



Tellina Groenlandica, Beck. 

 T. proxima, Brown. 

 T. (Macoma) inflata, Stimpson. 

 Mya arenaria, Linn. 

 M. truncata, Linn., var. Uddevallensis. 

 *Panopa3a Arctica, Gould. (P. Norvegica?). 

 Saxicava rugosa, Linn., and var. Arctica. 



* Lyonsia arenosa, Moll. 



Note. — Large suites of specimens from Riviere-du-Loup enable me to 

 determine with certainty that Leda tenuisulcata Couthouy, L. pernula 

 Muller, (& Wood, English Crag,) and L. Jacksoni Gould, are varieties 

 of one species ; that Saxicava Jlrctica is merely a variety of S. rugosa ; 

 and that Leda siliqua and L. sulcifera of Reeve are varieties of L. trun- 

 cata, which is identical with L. Portlandica Gould. 



GASTEROPODA. 



* Cylichna nucleola, Reeve. 

 Acmoea (Lepeta) caeca, Mull. 

 Cemoria Noachina, Linn. 



* Adeorbis costulata? 



Margarita helicina, Fabr., (Arctica). 



* M. cinerea, Couth. 

 Littorina palliata, Say. 



* L. rudis, Mont. 



Scalaria Grcenlandica, Perry. 



