lymnjewje of north America. 415 



took Co. It is unfortunate that Say's type specimens from Maine have 

 not been preserved. The two autotypes in the Philadelphia Academy 

 are from Saratoga Lake, New York, and do not accurately represent 

 the Maine form, being of a transition nature between typical emar- 

 ginata and the race called canadensis. The autotypes are rather small 

 and thin, have well rounded whorls, especially the body whorl, a con- 

 spicuous umbilical chink and a wide, erect inner lip which strongly 

 emargins the umbilical region. Say's original figure in the American 

 conchology (see PI. XXX, figures 27-28) represent the whorls as very 

 globose and the spire as short and rather blunt. Haldeman's figures 

 well represent the typical elongated form, though figures 4 and 5 ap- 

 proach the race called canadensis. 



Authors generally have taken the small, narrow shell with sharp 

 pointed spire as typical emarginata, but Say did not have this form in 

 mind, although he may have included it in his species. Typical emar- 

 ginata has a rather short, broadly pyramidal spire, the zvhorls being 

 well rounded, the body whorl quite convex, the aperture ovate or almost 

 round in some specimens, and the inner lip wide and broadly reflected, 

 overhanging the large, conspicuous umbilical chink. The distinguish- 

 able features of the shell are the rounded, sub-globose shape of the last 

 whorl, and the broad spire with the upper spire whorls broadly de- 

 pressed and flattened. Say remarks in his original description that 

 it is a larger and consderably wider shell than catascopium, and as he 

 figures a wide shell for this species (see plate XXX, figures 25, 26) 

 we must look for a still wider shell in emarginata, which is supplied 

 by the Maine and Michigan shells. Catascopium may be at once dis- 

 tinguished from emarginata by its narrower shell, and especially by 

 its inner lip which is narrow and closely appressed to the umbilical 

 region leaving at most only a very small chink. There is also a dis- 

 tinct plait in catascopium. 



In the Conch. Icon. Sowerby describes and figures a Limncea deli- 

 cata Say, which appears to be the same as emarginata. Say, however, 

 never described such a Lymnaea, and both the figure and description 

 show it to refer to some form of emarginata. The description is as fol- 

 lows: 



"Shell subfusiform, subpellucid, horny, pale rose-milky, spirally 

 slightly banded, spire elevated, slightly ladder-like; whorls four, con- 

 vex, rather angular, last whorl rather short, excavated behind the 

 columella; aperture subquadrate, posteriorly slightly angular, columel- 

 la tortuous, somewhat curved backwards." 



An examination of several thousand specimens of emarginata 



