THE NAUTILUS. 



VOL. XIV. JANUARY, 19O1. No. 9. 



NEW VARIETIES OF PHYSA ANCILLARIA SAY. 



BY BRYANT AVALKER. 



Physa ancillaria var. magnalacustris. 



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

 stronger toward the suture and somewhat irregular; transverse striae 

 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. 12|, diam. 11, length of aperture 11-J- mm. 



Alt. 17^, diam. 12^, length of aperture, 14t^ mm. 



Alt. 13^, diam. 10|, length of aperture 1<H nim. 



Types from Frankfort, Benzie County, 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 



