LYMX.EID.E OF NORTH AMERICA. 147 



Nevada : Rare specimens are found semi-fossil in the Humboldt sink in 

 the Lahontan area (Call). 



Ontario, Canada : Sand and gravel pits, Niagara Falls ; Leda clay, ten 

 miles below Ottawa city (Bell). 



Utah: It abounds, as a semi-fossil, in Sevier Desert (Call, Mollusca of 

 Great Basin). 



Ecology : Found usually in more or less stagnant spots of ponds 

 and rivers about decaying vegetation. In ponds it may be found float- 

 ing among pond weeds with its foot applied to the surface of the water. 

 A shore bordered with reeds and cat-tails is a favorite locality. Also 

 found on, and in the vicinity of, rotten fruit and vegetables, and fre- 

 quently seen feeding on the dead bodies of various animals. In the 

 small bays and inlets of Lake Ontario, this species is very abundant. 

 It has been noted that early in the year, about May or June, stagnates 

 is found only in small patches of water near the shore, while later in 

 the year, in August or September, it may be found in abundance float- 

 ing in the open water of these bays, particularly in the vegetation which 

 is so common at this time of the year. It breeds in the fall. 



"In a small pool along Bitter Root River. A large spring supplies 

 the pool with clear, fresh water. (Elrod, Montana.) 



''In lakes, feeding upon weeds. (Sargent, Minnesota.) 



"Outlet of Lake Tahoe, Placer County, Cal., 6247 ft. alt. (Cooper.) 



"The specimens from the prairie region are often very well grown 

 and robust, the shell being thick and showing strong growth lines. 

 Some specimens from pools at Dufterin measured 56 by 26 mill." 

 (Dawson, Manitoba.) 



Although generally supposed to be a vegetable feeder, stagnalis 

 is known not only to feed upon dead animals, but instances are on 

 record of its attacking living animals, especially fish (stickleback) 

 which have been confined with them in the aquarium. 1 The writer 

 has observed it adhering to rotting vegetables, dead dogs, cats and 

 other animals in the Erie Canal, at Rochester, N. Y. Mr. William 

 Nelson 2 records the presence of a pale violet liquid, which is discharged 

 by the animal when irritated and sometimes when lifted from the water. 

 The same phenomenon has been observed by the writer in many of 

 the American forms. 



Some interesting experiments in raising apprcssa from the egg 

 have been made by Dr. H. A. Pilsbry at the Academy of Natural 

 Sciences of Philadelphia. The specimen from which the eggs were 

 obtained was a large, fat individual of five whorls, from Buffalo, N. Y., 



*Ullyett, Sci. Gossip, XXII, p. 24. 1886. 

 2 Joum. Conch. I, p. 216, 1S78. 



