34 



LAND AND FRESH-WATER SHELLS OF ?f. A. [PART TI. 



Fig. 39. 



Limncea 

 macrostoma. 



Limnaea mucrostomn, Say. — Shell sulioval ; whirls five, body whirl some- 

 what reticulated ; suture not proloundly iudented ; s^pire 

 about two-thirds the length of the aperture, acute ; aperture 

 much dilated ; labrum uot thickened on the inner sub- 

 margin. 



Inhabits Cayuga Lake. Length J inch, and upwards. 



Imperfect specimens of this shell were found on tlie shore 

 of Cayuga Lake, by Mr. A. Jessup, but they are sufficiently 

 entire to exhibit considerable similarity to some varieties of 

 L. auricidarius, of Europe. It may readily be distinguished 

 fromL. catascopium by its much more dilated aperture. (.?«»/.) 



Limnsea acuminata, Adams, seems a synonym of L. columella. 

 Haldeman and DeKay so consider it, and Gould refers it to L. 

 macrostoma. I have seen no authentic specimen, but give the 

 original description below. It must not be confounded with 

 Brongniart's species of the same name. 



Limnsea acuminata, Adams. — Shell fragile, semi-transparent, ovate, with 

 very numerous, revolving, irregular, transverse, parallel strise ; whirls four ; 

 spire very short, subacute ; last whirl very large ; aperture very large, 

 exhibiting the interior of the spire ; columella thin, sub-reflected ; labium 

 not appressed. 



New Bedford. 



This differs from L. columelln, Say, in the much greater proportional 

 size of the last whirl, the breadth of the shell, and the presence of very 

 distinct revolving lines. It resembles Succinea ohliqua, Say, but the spire 

 is rather less, and no revolving lines are mentioned in the description of 

 that species. The L. acuminata has also been found at Uorn Pond, in 

 Woburn, Mass., by T. J. Whittemore, Esq. {Adams.) 



Limnsea chalyhea, of Gould, whose description and figure are 

 here copied, is no doubt a form of L. columella. It is so stated 

 by him recently (Otia, p. 180), as well as by Haldeman in his 

 Monograph. 



Limnaea columella, var. rhalyhea', Gopld. — The spire is more pointed, its 

 divergence only about 50^ ; the aperture is more expanded, 

 and the fold ou the inner lip more obvious. It is thin, but 

 not very brittle, ringing like hard-burnt crockery. The last 

 whirl is partially detached from the preceding one, so as to 

 form a thread-like channel at the suture. The enamel rests 

 loosely against the shell, and is wrinkled. The exterior is 

 covered by a bluish-black pigment, not easily removed, and 

 the interior has a steel-blue or black lead color. 



This shell, which I found two years in succession in a 

 muddy I'ool in Cambridge, I thoiight was siiffioiently distinct 

 to be regarded as a new species ; and I accordingly gave its 



Fig. 40. 



