MOLLUSCS, VERMES AND HYDROZOA 



Eastern and Middle States and there is but one in the Southern States, 

 L. pilsbryi of the Chipola River, Florida, a very rare species. 



Valvata. These small snails never exceed %. to ^4 inch in diameter 

 and are principally prized on account of their odd appearance and the 

 curious formation of their water-breathing organs or branchia. Most of 

 the species are almost exclusively vegetable feeding and destructive to 

 plants, and but few should be introduced into the aquarium, though they 

 are comparatively harmless, due to their small size. 



V. tricarinata. Fig. 149, has a slightly depressed turbinate, translucent 

 yellowish-and greenish-brown shell i^ inch in diameter, of three to four 

 smooth whorls with faint 

 lines of growth and flat- 

 tened spire. The body 

 is slightly translucent, the 



plume-like branchial fila- ^^'^- ■49- f^ahata tricarinata. Enlarged. 



ments long, the eyes black, the posterior of the foot extending nearly to the 

 circumference of the shell, and the thin operculum near the extremity of 



the foot. It is ovi- 

 parous and vegetable 

 feeding and inhabits 



FIG. 150. Val-vata hicarinata. Enlarged. the EaStem and 



Middle States generally, with a kindred slightly larger variety, V. hicarinata. 

 Fig. 150, native in the Schuylkill river and its tributaries. It is about 

 l^inch in diameter. 



V. sincera. Fig. 151, has a globose-discoidal faintly striated brownish- 

 green shell, consisting of three and a half accurately rounded whorls which 

 enlarge rapidly from the apex. The suture is deeply impressed, the spire 

 flattened and the apex 

 obtuse. This snail is 

 seldom over ^ to ^ 

 inch in diameter and 

 occurs in Vermont and "°- '5'- ^''■^■"''•'' """'■<'■ Enlarged, 



the Northwestern States. There are other species of the Valvata but they 

 do not occur in the Eastern or Middle States. 



Ampullaria. This family has no members inhabiting waters of the 

 Eastern and Middle States. All the species are large and handsome; but 

 as their size would lead to the inference that they would be destructive to 

 aquarium plants, experiment would be advisable before introducing them, 

 as their food is vegetable and those kept in confinement eagerly devour 

 lettuce. They are nocturnal in habits and seldom appear out of the shell 

 during the day. They are interesting inmates for the Terra-aquarium. 



225 



