FAMILY AMNICOLID^E 117 



Range. Northern California, Oregon and Washington. 



Vancouver Island (Forbes) ? British Columbia in streams west of 

 the Cascades (Lord). 



This species so much resembles the viviparous Melania of the Ha- 

 waiian Islands and the Orient, which has a fringed mantle edge, that 

 for a long time it was doubted whether the little group of Pacific 

 Coast species was not related to the oriental forms rather than to the 

 Goniobasis of the eastern United States. An examination of the liv- 

 ing animal by the writer a few years ago showed, however, that the 

 Oregon species has a plain mantle edge and is oviparous, so that the 

 resemblance referred to, though obvious, is probably merely the 

 result of convergence, and expresses no intimate relationship. 



Tryon regarded Gould's silicula as a species ; others have thought it 

 a variety of the older plicifera. Further studies are necessary to de- 

 termine the question. 



Family AMNICOLID^. 

 Genus Amnicola Gould and Haldeman. 

 Amnicola limosa Say. 



Paludina limosa SAY, Journ. Acad. Nat. Sci. Phila., I, p. 125, 1817. 

 NICHOLSON'S Encyc., third American ed., p. 12, 1819. 



Paludina porata SAY, Journ. Acad. Nat. Sci. Phila., II, p. 174, 1821. 



Amnicola porata GOULD, Inv. Mass., p. 229, fig. 157, 1841. 



Amnicola limosa HALDEMAX, Mon. Limn., p. 10, pi. i, figs. 5, 6, 1845. 

 BIXXEY, Land and Fw. Sh. N. Am., in, p. 84, fig. 166, 

 1865. 



Lyogyrus lehnerti ANCEY (MoxsxR.). 



Range. Virginia to Wisconsin and Hudson Bay. 



Lake Superior to the Height of Land ; Athabaska . Fl , G ',? 4 * Am ~ 



,.,-,.,, \-HTT so nicola limosa. 



at Lake La Loche (Richardson), N. Lat. 56 30' ; 



Lake of the Woods ; Manitoba ; Moose Factory, Hudson Bay ! Big 

 Sioux River, Nebraska ! Salt Lake basin, Utah Lake ! Utah. 



This is the type of the genus, and it seems to reach 

 <& the headwaters of the Atlantic and Hudson Bay drain- 



\(j age but not to reach the drainage on the other side of 



FIG. 85. Am- the watershed alluded to. 

 nicola pallida. 



Amnicola pallida Haldeman. 



Amnicola pallida HALDEMAX, Mon. Limn., pt. m, cover p. 3, 1842, pt viu, 

 p. 12, pi. I, fig. 7, 1845. BIXNEY, Land and Fw. Sh. N. Am., in, p. 

 83, fig. 165, 1865. 



Range. New York northward to Canada and Manitoba. 

 Lake Winnipeg, Brandon, and Pine Creek, Manitoba. 



