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AMERICAN JOURNAL 



of the stream is mud. The other (Goniobasis JYiagarensis, Lea,) 

 abounds only where the current is somewhat rapid, and is found 

 in the utmost profusion adhering to rocks. 



Remarkable for its large size, a species of Succinea (referred 

 by Mr. Binney as a variety to Say's avard) is found on the 

 shaded alluvial soil along the banks of the Mohawk. The 

 average size of adults is a little less than half an inch in length. 

 Specimens are sometimes found eleven-twentieths of an inch long. 

 This unusual development may be sufficient ground for regarding 

 these molluscs as a distinct species from avara, the usual length 

 of which is seldom much greater than a quarter of an inch. 



This Succinea is remarkable for exhibiting vagaries of habit 

 somewhat perplexing to the collector. In some seasons it 

 abounds in great numbers and attains its greatest perfection of 

 development, after which it may so entirely disappear for a num- 

 ber of years as wholly to elude search for it. In this respect it 

 exhibits some of the peculiarities which collectors near Portland, 

 Maine, have remarked of the species of Vitrina found there. 

 Similar irregularities in habit have also been observed in 

 Sphcerium transversum, Say, which is sometimes found quite 

 plenty in the Erie canal, after which for one or two seasons 

 scarcely any can be found. 



Among the rare species (rare everywhere, so far as is known), 

 mention may be made of Helix S'ayii, Binney, which until 1868 

 never could be found except by accident, and that only at remote 

 intervals. In fact less than half a dozen presentable specimens 

 are all that have been seen since 1853 until the present season, 

 when careful search, having this species in view, revealed them in 

 somewhat encouraging numbers. In May and June of this year 

 a careful examination was made of the steep hillsides of a ravine 

 a mile east of Mohawk village. A spare growth of new forest 

 covers these hillsides with a moderate shade, and the leaves from 

 the trees falling into little crevices in the soil afforded shelter for 

 the snails. The soil is a mixed argillaceous and sandy drift 

 overlaying " Utica slate." Other species of Helix were found 

 here in considerable abundance. H. Sayii yielded about ten 

 specimens. In September five- more were found. The older 

 woodlands in the higher parts of the ravine yielded none of H. 

 Sayii, but presented a few specimens of another rare species, 

 H. inomata, Say. Helix palliata, Say, formerly an available 

 species here, seems now to have become rather extinct, or so rare 

 as to escape observation. Physa hypnorum, once an abundant 

 species in the little pools that are sometimes found in natural 

 depressions shaded by woods, seems no longer to have a domicil 

 with us. 



