FAMILY PHYSlDyE lOI 



? Section Macrophysa Meek. Shell elongate, columnar, large, the 

 last whorl and aperture small compared with that of the typical 

 Physa^ the surface axially striated. Type Pliysa colunniaris 

 Dcshaj-es, Eocene of Paris Basin. 

 Section Costatella Dall. Shell physiform, polished, sculptured with 

 axial ribs. Type Physa costata Newcomb. 



The section Macrophysa has been affiliated to Isidora by Sandberger 

 and others, but as the species is only known in the fossil state some 

 doubt must remain as to its relations. It has somewhat the form of 

 Isidora waJilbcrgi Krauss from South Africa, but the resemblance 

 may be merely a parallelism and not an indication of relationship, as 

 we find several species of Isidora absolutely indistinguishable from 

 true Physa except by anatomical examination. 



The groups known as Amcria A.i\ami, Glyptophysa Crosse, Plcsio- 

 physa Crosse and Fischer, Physopsis Krauss, Piilmobranchia Pelsen- 

 ear, etc., are more or less intimately connected with Isidora Ehrenberg 

 {Bulinus Adanson) and do not form part of the family Pkysidic. 

 None of them occurs in the region to which this paper relates. I am 

 indebted to the discussion of American Physa; by O. A. Crandall in 

 the Nautilus, voliune xv, for assistance in determining the species of 

 Physa from the north. 



Physa heterostropha Say. 



Physa heterostropha Say, Nicholson's Encycl., Am. ed. (no pagination), pi. 



I, fig. 6, 1817. — Haldeman, Mon. Limn., p. 23, pi. 11, figs. 1-9, 1843. 



— Bl.\NEY, Land and Fw. Sh. N. Am., II, p. 84, figs. 144-5, 1865. 

 Physa plicata De Kav, fraoilis Mighels, hita Tryon, pri)>irana Trycni, and 



philippii Kiister, are said to be synonymous by Crandall. 



Range. — From the Potomac and Ohio Rivers /^ 



northward, and westward to the Mississippi. (\\&}\ 



Anticosti Island ! Manitoba, Red River of the I ^W 



North, Lac des Mille Lacs to Lake of the Woods ; 



Alberta, at Olds, McLeod and Red Deer. Grand , . , ^i 

 ' ' heterostrop/ta. 



Rapids of the Saskatchewan ! L. Winnipeg ! English 

 River ! Albany River ! near James Bay ; Hudson Bay drainage in 

 Keewatin at Moose Factory ! and Nelson River 1 Lake Isle Lacrosse ! 

 Peace River ! and Great Slave Lake ! 



Readily recognizable by its form and the absence of microscopic 

 spiral sculpture. The northern specimens, when dead, are of a beau- 

 tiful opalescent white with a claret colored apex. 



Physa gyrina Say. 



Physa gyrina Sw, Journ. Acad. Nat. Sci. Phila., 11, p. 171, 1821. — Halde- 

 .man, Mon. Limn., p. 32, pi. 3, figs. 1-6, 1843; Coimcil Bluffs, Iowa. 



