134 HELICID^. 



We are induced, by the examination of a large number 

 of examples, collected from various and remote localities, 

 and more particularly by the interesting series kindly 

 communicated to us by Mr. Alder, to re-unite the S. 

 Pfeifferi to this species. It is easy to pick out certain 

 individuals, which unite in themselves all the peculiarities 

 of character from which the variety (for such we hold it) 

 has been regarded as specifically distinct, but a still larger 

 proportion of specimens exist, which, from their mixed 

 characteristics, can be assigned with certainty to neither 

 form ; and these connecting links (not mere hybrids, but 

 living in separate little communities) forbid, as we con- 

 ceive, any essential separation of the forms of common 

 Succinea. 



The shell is very thin, pellucid, glossy or lustrous, and 

 of an uniform tint that ranges from rufous orange, through 

 amber and yellow to pale straw colour. The shape varies 

 from ovate-conic or oval-acute to narrow oblong conic : the 

 surface exhibits neither folds, spiral sculpture, nor reticula- 

 tions, but is more or less manifestly marked with crowded 

 wrinkles of increase. The whorls, whose apex is small, 

 but not acute, are from three to three and a half in num- 

 ber, of rapid longitudinal increase, taper above, rounded 

 below ; and in the more produced or slender form, are for 

 the most part planulate or even a little subretuse beneath 

 the strongly pronounced suture, which latter, by the amount 

 of its obliquity and occasional final deflection, modifies 

 greatly the general contour ; the slant is least in short- 

 spired ventricose examples. Five-sevenths of the dorsal 

 length, sometimes even four-fifths, more rarely only three- 

 fifths, are occupied by the body-whorl, whose basal decli- 

 nation is more or less rounded and gradual. The aper- 

 ture, which is contracted above, and broadly rounded 



