374 



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



of an inch. Length of aperture, seven-sixteenths ; breadth of aper- 

 ture, three-sixteenths of an inch. 



Observations. — This is the most cylindrical species I have ever seen 

 in this genus. In its general form and coloring it most nearly re- 

 sembles G. demissa (nobis), but is longer, more elevated, smoother 

 and is ornamented with bands, ■which on that species are entirely 

 wanting; these bands on the body-whorl are three in number, of 

 which the middle one is the narrowest and leiist distinct; they are 

 widely distant from each other; the cord-like cincture is very prom- 

 inent in this species and the Assure is farther removed from the 

 suture than is usual. It is altogether a beautiful and graceful spe- 

 cies. — Anthony. 



Mr. Lea's description, being founded on a single abnormal 

 specimen, is by no means so good as that of Mr. Anthony ; I 

 have, therefore, adopted the latter. The types of both are 

 figured. I have seen other specimens besides Mr. Lea's, 

 which have the constriction of the centre of the whorls, 

 which has given rise to the specific name, but I cannot at 

 present consider this to be a normal character of the species. 

 Mr. Reeve's fig. 7a represents a smooth variety of salebrosum, 

 Anthony. Mr. Lea's description and figure are given below. 



Schisostoma constrictum. — Shell smooth, somewhat fusiform, rather 

 thin, yellowish horn-color; spire obtuse; sutures impressed; whorls 

 Fig. 705. Fig. 700. constricted ; fissure rather large, somewhat ob- 

 lique; aperture large, elliptical, whitish within; 

 columella smooth, subangular at the base. 

 Habitat. — Tuscaloosa ; Alabama. 

 Diameter, '43; length, '75 of an inch. 

 Observations. — A single specimen only of this 

 species was among the shells submitted to me by Dr. Budd. It dif- 

 fers from those I have seen in having a rather broad channel im- 

 pi'essed immediately above the centre of the whorl. This character 

 may, however, differ in other individuals. The fissure is rather wide, 

 but not deep. The apex being eroded, the number of whorls could 

 not be ascertained. The aperture is about one-half the length of the 

 shell. There is no appearance of bands about this specimen. — Lea. 



