MOLLUSCS. 



315 



This species is an article of food and is sold in the markets of Rio Janeiro. Its eggs are 

 also very large ; they have a white calcareous shell, and equal in size those of a pigeon. 



Fig. 374. — Helix palUata. 



Fig. 375. — Helix sayi. 



Fig. 376. — Helix dentifera. 



In the older works several species of Bulimus were credited to the United States, 

 but more recent studies show that these forms belong elsewhere in schemes of classifi- 

 cation. 



In some of the South Sea Islands, especially in the Society group, occur a number 

 of land shells united under the generic name Partula. These are brightly colored and 

 much like Buliniiis in shape. Formei'ly they were very abundant ; but a few years ago 

 a great storm utterly destroyed the groves in which they were found and almost extin- 

 guished the genus. Unlike most of the pulmonates they bring forth their young alive, 



Fig. 377. — Achatina maurita/nica. 



and the shells are more frequently sinistral than in the other genera of the Helicidse. 

 In the genus Binneya occurs a peculiarity first noticed by Dr. J. G. Cooper. The 

 species are all inhabitants of Mexico and Southern California. At the approach of the 

 dry season they retreat as do the Helices of more northern climes in the winter. Still, 

 as the shell is too small to contain the whole body, the epiphragm is greatly enlarged 

 so that it covers all the parts which would otherwise be exposed. This epiphragmal 

 envelope is white and parchment-like. 



