

The Nautilus. 



Vol. XIV. JANUARY, 1901. No. 9. 



NEW VARIETIES OF PHYSA ANCILLARIA SAY. 



BY BRYANT WALKER. 



Physa ancillaria var. magnalacustris. 



Shell subglobose, thick, solid, semi-opaque ; incremental striae fine, 

 stronger toward t lie suture and somewhat irregular; transverse stria? 

 very minute or subobsolete ; purplish-horn color, darker toward the 

 apex, which is dark brown or black ; body whorl with one or more 

 broad white varicose bands, more or less suffused with white toward 

 the lip and at the base; whorls 5, regularly and rapidly increas- 

 ing, the first minute, the last very large, regularly rounded, not 

 shouldered, the greatest width being in the centre; spire slightly 

 elevated, acute ; suture but slightly impressed, margined below with 

 white; aperture large, expanded below so that the greatest width is 

 below the centre; outer lip thin, sharp, more or less expanded and 

 broadly rounded below ; thickened within by deep yellowish-brown 

 or liver-colored callus, which appears externally as a broad white 

 band, extremities connected by a thin callus, which is broadly re- 

 flected over the body whorl : columella white, straight, scarcely 

 twisted. 



Alt. 12f, diam. 11, length of aperture 1H mm. 



Alt. 17^, diam. 12^, length "I' aperture, 14^ mm. 



Alt. 13^, diam. 1(H, length of aperture 1(H ' lim - 



Types from Frankfort, Benzie ( founty, Michigan. It has also been 

 found at Charlevoix, Beaver Islands, Mackinac Island, Mackinaw 

 City and Port Austin, Huron County, Michigan. These localities 

 indicate distribution along the coast-line of the upper part of the lower 



