68 LAND AND FRESH WATER MOLLUSKS 



Lymnaea (Radix) mighelsi Binney. 



UmncEa decollata Mighels, Proc. Boston Soc. Nat. Hist., i, p. 49, 1841. 



MiGHELS and Adams, Boston Journ. Nat. Hist., iv, p. 336, pi. iv, fig. 13 

 (four views), 1842. 



Livtnea catascopium Haldeman, Mon. Limn., p. 52, 1842 ; not of Say, 



UmncEus decollatus Kuster, Conch. Cab., ed. 11, Mon. Limn., p. 45, pL 

 VIII, figs. 11-14, 1862. 



LimncEa ampla Mighels, Boston Journ. Nat. Hist. , iv, p. 347, pi. xvi, figs. 

 \a-ic, April, 1843 ; not of Hartmann, 1842. — Binney, Land and Fw. 

 Sh. N. Am., II, p. 30, figs. 34-35, 1865. 



Limncea mighelsi, W. G. Binney, Land and Fw. Sh. N. Am., 11, p. 31, foot- 

 note, 1865. 



Limncea angulata Sowerby, Conch. Icon. , xviii, Mon. Hmncea, pi. vii, fig. 

 47, Dec, 1872. 



Umnaa emarginata Say, var. mighelsi Binney, Nylander, Distr. of Limncea, 

 etc., pis. i-iv, 1 90 1. 



Range. — Aroostook Co., Maine; Province of Quebec; northern 

 Michigan } 



Aroostook Co., Maine ! Brome Lake, Province of Quebec ! Lake 

 Namakan, north of Lake Superior, western Ontario ; Lake of the 

 Woods, Manitoba. 



The earliest name of this species is decollata.^ which was applied to 

 a stunted variety living in acidulous water which destroyed the early 

 whorls. This name, however, being quite inapplicable to the normal 

 shell, would best be kept for the shells to which it was 

 applied, and retained in a varietal sense. After an 

 examination of Say's types of Z. emarginata I am 

 quite confident, as species go in Lymncea^ that it is 

 distinct from the present form, which I have never 

 seen from the Western region. This species, L. 

 ' . ' . J mighelsi^ is apparently a representative of Radix ^ 

 while the thickening of the outer lip internally in 

 Z.. emarginata var. canadensis leads to the suspicion that it is 

 related to Stagnicola. Owing to the manner in which various forms 

 of emarginata have been summarily united with Z. mighelsi by rep- 

 utable students, I shall on the present occasion waive this doubt and 

 proceed to its immediate consideration. It may, however, be pointed 

 out that W. G. Binney seems to have been of the same opinion when, 

 in 1865, he placed Z. emarginata in the same group as Z. falustris. 



Lymnaea (Stagnicola.?) emarginata Say. 



Lymneus emarginatus Say, Journ. Acad. Nat. Sci. Phila., 11, p. 170, 1821 ; 



Long's Exp. Rep., 11, p. 263, 1824 (Maine). 

 f Umneus emarginatus Say, Am. Conch., vi, pi. 55, fig. I, 1834. 

 Limneus ontariensis Muhlfeldt in Kuster, 1Z62, fide W. G. Binney, op. ch., 



p. 52, 1865. 



