SUCCINEA. 63 



in the absence of such means of comparison, been com- 

 pelled to rely on descriptions alone, and consequently 

 some erroi's have been committed ; and there is a want 

 of a common understanding as to the species referred to 

 by him, imder his respective names. And J\Ir. Say him- 

 self, preparing his descriptions under inconvenient cii-- 

 cumstances, and at great intervals of time and position, 

 has apparently sometimes repeated his own species. 

 Owing to the slight variation of specific form which 

 prevails in the Limacidce and in this genus, it is in these 

 that the greatest amount of discrepancies occur. We 

 give here Mr. Say's names and descriptions. 



" Succinea ovalis. Shell sub-oval, pale yellowish, diaphanous, 

 very thin and fragile, with nearly three oblique volutions. 

 Body very large. Spire small, but little prominent, some- 

 what obtuse. Aperture longitudinally sub-ovate, large. Col- 

 umella much narrowed, so as almost to permit the view of 

 the interior spire. Length nine-twentieths. Aperture seven- 

 twentieths of an inch. 



" Succinea campestris. Shell oval, very fragile, whorls three, 

 not remarkably oblique ; pale yellowish, with opaque white 

 and vitreous lines irregularly alternating. Length not quite 

 three-fifihs ; breadth seven-twentieths of an inch. 



" Succinea avara. Shell sub-oval, pale reddish yellow, sub- 

 diaphanous, fragile, covered with an earthy crust ; whorls 

 three, minutely wrinkled; body whorl very large; spire 

 small ; aperture large, sub-ovate, about two thirds of the 

 length of the shell. Length three-twentieths of an inch. 



" Succinea ohliqua. Shell oblong-oval, nearly pellucid, pale 

 amber-colored ; whorls three, very obliquely revolving, dis- 

 tinctly wrinkled ; spire a little prominent ; aperture sub-oval, 

 somewhat oblique. Length seven-tenths of an inch. 



