THE MOLLUSKS OR SHELLFISH 



land snails. He described the sound as resembling that of hundreds of 



harps, and believed it was produced by the friction of the shell against the bark of 



the trees upon which the snails were crawling. 



The amber-snails {Suctineidce) bear a strong family likeness to one another. 

 The shells are all very fragile, oblong, yellowish, or reddish, with a more or less 

 exserted spire and a very large body whorl. They are found in damp situations, 



and have even been observed crawl- 

 ing beneath the water, upon which 

 they can float in a reversed position. 

 They are vegetarian in their diet, 

 and deposit their eggs on the stems 

 and leaves of aquatic plants, and 

 also upon stones or other substances 

 near the water's edge. Species of 

 Succinea occur in most parts of the 

 world, being met with in such re- 

 mote localities as Greenland. Pata- 

 Pythia scarabceus. 

 (Natural size.) goma, India, Japan, Australia, and 



the South Sea islands. The species 



figured on page 3312 is found all over Europe and ranges even as far as Afghanistan. 

 The characteristic of the radula is shown in the figure on the next page. 



The family Ontidiidce includes about fifty shell-less air-breathing mollusks, 

 somewhat slug-like in general appearance, but provided with a thick mantle cover- 

 ing the whole dorsal region. This is frequently more or less tubercular, some of 

 the tubercles being furnished with eyes which, simple as they are in structure, are 

 identical in type with those of the Vertebrata. These snails live on the seashore 

 or in brackish marshes, eating nothing but sand, but, of course, only digesting the 

 nutritious organic particles contained in it. Professor Semper has given an account 

 of their habits, and how they are pursued by certain fishes (Periophthalmus} which 

 come ashore after them. One species, 

 O. celticum, is found in Cornwall and 

 South Devon, others occur in Amer- 

 ica and the Pacific. 



The numerous 



forms belonging to this 



group, comprising the 

 rest of the Pulmonata, differ from 

 those already indicated, in having 

 the eyes situated at the base of the 

 tentacles, as in the marine whelks 



Basomma- 

 tophora 



EARI.ET SHEI.L, Auricula judce. 

 (Natural size.) 



and periwinkles, instead of at the tips. 



An external shell is always present, 



and capable of containing the entire 



animal. The members of the family Auriculidce mostly inhabit salt or brackish 



marshes, and were formerly regarded as marine mollusks. The shells generally are 



