MOLLUSCS, VERMES AND HYDROZOA 



FIG. 1 66. Lymnaa decidiosa. Enlarged. 



body partly translucent with 

 the central portion light brown. 

 The tentacles are short and 

 mottled with black. It in- 

 habits the Eastern coast States 

 from Maine to South Carolina, 

 and west to Ohio and the 

 FIG. 165. L,.»,«^<. «&««//«. Enlarged. Northwestem States. The 



spawn is deposited in irregular patches of 50 to 100 and hatch in about 20 

 days. This species is similar to Succinea, but may be distinguished by 

 the spiral line on the shell and the fold on the columella. 



L. decidiosa, Fig. 166, has a somewhat inflated thin translucent light- 

 ochre or brownish % inch long shell, showing faint lines of growth. The 

 spire is rapidly attenuated to an acute 

 point, and the five whorls are sep- 

 arated by a deep suture, the aperture 

 being one-half the length of the shell. 

 The body is light yellowish-grey, 

 minutely dotted with white; and the 

 tentacles short, broad and translucent. 

 Its range is from New England to the Mississippi and it inhabits rivulets 

 and small lakes. 



L. catascopium. Fig. 167, is very similar to L. putris of Europe and 

 has a smooth and polished ^ inch long greyish or yellowish-brown shell 

 with lightly marked lines of growth, and is darker at the apex, with 



four or five convex whorls of 

 which the body whorl is large, 

 the suture well defined, the 

 spire tapering to an acute point 

 and the aperture one-half the 

 length of the shell. The body 

 is yellowish-brown sprinkled 



YIG. ^e^.Lyn,naacatascofiun,. ^j^}^ light-yelloW SpOtS; the 



tentacles are short and the translucent foot as long as the aperture. It 

 inhabits the rivers and streams of Massachusetts and New York near 

 Niagara Falls, and the Delaware and Schuylkill rivers; and is one of the 

 most frequently met with species. It is often introduced into the aquarium 

 with plants. The 20 to 40 eggs are deposited in a transparent yellowish 

 capsule which hatch in about i 6 days. 



All the native Lymnaea should be only sparingly introduced into the 

 aquarium as they make havoc with the plants. Some species sever the 



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