MOLLUSCS, VERMES AND HYDROZOA 



FIG. 163. Niagara Snail, Lymmea stagnalis. , 



deep and the ap- 

 erture oval. The 

 body is yellowish- 

 grey with a green- 

 ish tinge, spotted 

 with brown- and 

 the tentacles flat, 

 triangular and 

 have a backward 

 trend. It is ovi- 

 parous and the 

 70 to 150 eggs, 

 deposited at in- 

 tervals in cylindrical capsules, hatch in 1 5 to 20 days. This is one of the 

 most handsome snails, of which a pair or two may be kept in the aquarium 

 without damage to the plants. Its range is over the entire northern latitudes, 

 and in the United States is found from Vermont through the Northern tier 

 of States to the Pacific Ocean. It is popularly known as the "Niagara Snail." 

 L. palustris, ¥\g. 164, is a destructive though interesting common 

 snail found in nearly all ditches, ponds and streams in the Eastern Atlantic 

 slope and in Europe. The conical shell is ^ to 1 54^ inches long, of a light 

 horn-color on the body 

 whorl and usually a 

 dark horn-color, brown 

 or black above. It has 

 five or six whorls sep- 

 arated by white lines, 

 with the body whorl 

 half as long as the shell. 

 The ovate aperture is "«• ■^4- Lymnaa paiuuru. 



nearly as long as the body whorl and the suture is deeply depressed. The 

 body is dark gray or nearly black, with a violet tint, faintly spotted with 

 yellow and black, and the tentacles flat and conical. It ranges from New 

 England through Pennsylvania and south. Its habit of coming above the 

 water serves as an identification in the aquarium, into which it is sometimes 

 introduced with aquatic plants. The 60 to 80 eggs are deposited in a 

 cylindrical capsule and hatch in 12 to 20 days. 



L. columella. Fig. 165, has an ovate thin and fragile ^ to %; inch long shell 

 of four whorls crossed by minute lines of growth. The suture is deeply im- 

 pressed and conspicuous, the spire narrow and the aperture larger than 

 half the length of the shell. The body whorl is large and expanded, and the 



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