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THE CANADIAN NATURALIST. [Vol. 



Mya truncata, Linn., and variety Uddev alien sis. — Recent. 

 Greenland to Massachusetts Bay. — Littoral to Coralline. — 

 Fossil, R. C, B. P., St. J., St. A. Frequent. The long form 

 occurs in the clays at St. John, but the variety is more preva- 

 lent. 



Mya arenaria, Linn, and var. acuta. — Recent, Greenland to 

 Long Island Sound.— Littoral.— Fossil, R.C., B.P., T. R., St.J., 

 St. A. I have found this species only in the Saxicava sand. It 

 is now one of the most abundant molluscs on our coast. The 

 variety which is probably Say's Mya acuta, is distinguished by 

 being markedly ovate in form : it is inflated and expanded in 

 front, and the posterior slope from the hinge is much straighter 

 than in the typical form. The variety is by far the most abundant 

 shell in the Bay Chaleur clays, but the Myas of the St. John 

 beds are of the ordinary form. It may therefore be conjectured 

 that the var. acuta is of northern origin. 



Saxicava rugosa, Linn., and var. arctica. — Recent, Greenland 

 to Long Island Sound. — Littoral to Coralline. — Fossil, R.C., B. 

 P., T. R., St. J., St. A. This very variable species is more 

 abundant in the deposits of the St. Lawrence Valley and Bay 

 Chaleur, than in those of the Bay of Fundy. In going south 

 from the St. Lawrence R. the more regular forms, such as &. 

 rugosa and S. pholadis, increase in number, and the distorted 

 varieties S. arctica, S. rhomboides and S. hiatella decrease. For 

 instance in a collection made at Riviere du Loup, for which I am 

 indebted to Dr. Dawson, I find all but two are distorted forms; 

 in Mr. Chalmer's collection from Bay Chaleur the irregular ones 

 still predominate, and two-thirds of the shells would fall into 

 the varieties arctica, &c. ; but in the shells collected from the 

 Bay of Fundy clays, this proportion of distorted to regular forms 

 is reversed ; at St. Andrews one third only are of arctic types j 

 and of those collected at St. John, only one-fifth. In the speci- 

 mens of this species sent to me by Dr. Packard from Brunswick, 

 Maine, all the shells are regular, but one has the beak at the 

 anterior fourth of the valve. 



Lepralia hyalina, Johnston, Leda clay, St. John. 



Membra nopora pilosa, Johnston, Leda clay, St. John. 



Ctllepora pumicosa, Ellis, Leda clay, St. John. 



In this list there are more than thirty species of mollusca, a 

 number large enough to enable us to draw inferences, imperfect 



