358 LAND AND FRESH-WATER SHELLS OF N. A. [pART IV. 



Lea's figure of S. pumilum, and the smallest with S. globosurriy 

 with the aid of the intermediate figure (Fig. G78), will exhibit 

 their connection and the mode of growth of the shell. It will 

 be seen that S. glohosum has attained to four whorls, that the 

 intermediate figure would exhibit (if the loss by erosion were 

 supplied) five, and that the adult has six whorls. 

 The following is the description of 



Schizostoma glohosum. — Shell transversely striate, globose, rather 

 thin, yellowish, imperforate ; spire short, obtusely conical ; sutures 

 impressed; whorls four, three-banded, the last large; lip-cut straight, 

 narrow and short; aperture rather large, elliptical, banded within 

 and angular at the base ; columella white, incurved ; outer lip sharp 

 and expanded. 



Operculum ovate, rather light brown, with the polar point near the 

 inner lower edge. 



Habitat. — Alabama; E. R. Showalter, M.D. 



Diameter, '32 ; length, '48 of an inch. 



Observations. — This is a very small, globose species, more rounded 

 and inflated than anj' other which has come under my notice, and it is 

 Fig. 680. the smallest which I have seen. The description being made 

 from two specimens only, it may be found to vary when 

 |j\ others are observed. In this specimen the three bands are 

 y broad and of a dark brown, the two upper ones having on the 

 outside raised striae running parallel to the edges. The aperture is 

 iarge, and is rather more than half the length of the shell. The im- 

 pression made by the lip-cut is well defined and forms a narrow, 

 hem-like line below the suture. This species is not likely to be con- 

 founded with any of the species known, being smaller than all but 

 laciniatum (nobis), which is more conical. The aperture is nearly 

 two-thirds the length of the shell. — Lea. 



The analogue of S. pumilum among the obliquely fissured 

 species is S. Bucldii, Lea, to which it perhaps more nearly ap- 

 proximates than to either &'. glans or glandula, with which 

 Mr. Lea compares it. Although many of the shells in Reeve's 

 Monograph are well figured, their value for the ideiitification 

 of species is seriously impaired by the application to them in 

 several instances of wrong names, and by the insufficiency of 

 the descriptions. This is greatly to be regretted and illus- 



