, LYMN^ELLVE OF NORTH AMERICA. 



RADULA: With bicuspid lateral teeth (pi. VI, fig. N). 



GENITALIA: Penis shorter than penis-sac; prostate short, elon- 

 gate-ovate, its proximal portion rather roundly pointed as it joins the 

 duct; receptaculum seminis generally ovate, rarely round; the first 

 accessory albuminiparous gland is ovate and is placed lower down on 

 the oviduct than in Stagnicola (pi. XI, fig. A). 



This subgenus contains the smaller Lymnaeas which have a shell 

 without strong spiral sculpture. They exhibit terrestrial habits to a 

 much larger extent than do any of the other groups of Lymnaeas, being 

 found usually on wet banks or bars of mud, quite out of the water. 

 The formation of the inner lip is quite peculiar and will at once dis- 

 tinguish these small species from their larger relatives. The subgenus 

 is widely distributed, being found from the West Indies and southern 

 Mexico to the Arctic regions. Its maximum development is reached 

 in the southwestern portion of the United States. 



Galba truncatula (Muller). Plate XXVII, figures 1-4. 



Bucdnum truncatulum MULLER, Verm. Terr, et Fluv., II, p. -130, 1774. 

 BAKER, Science, N. S., XXVII, p. 943, 1908. 



Limneus minutus DRAPARNAUD, Tableau, p. 51, 1801; Hist., p. 53, pi. 3, 

 figs. 5, 6, 1805. 



Limnea truncatulus HALDEMAN, Bos. Journ. N. H., IV, p. 468, 1844. 



Limncca truncatula WOODWARD, P. Z. S., 1856, p. 185; Manual, p. 399, 

 1856. CARPENTER, Rep. Brit. Ass., 1856, p. 222. GRAY, Ann. Nat. Hist., XIX, 

 p. 408, 1857. MORCH, Amer. Journ. Sci., IV, p. 33, 1868. GIBBONS, Journ. Conch., 



II, p. 129, 1879. CLESSIN, Mai. Blatt, N. S., I, p. 20, 1879; Mai. Blatt., N. S., 



III, p. 77, 1881. JORDAN, Nova Acta Ksl. Leop. Carol.-Deutschen Akad. Natur., 

 XLV, p. 367, 1883. 



Lymncea (Galba} truncatula DALL, Land and Fr. W. Moll., p. 72, fig. 49, 

 1905 (part). 



Limn&a humilis DALL, Proc. Nat. Mus., VII, p. 343, 1884 ; Rep. Seal. Inves., 

 Ill, p. 544, 1899. 1 (?) 



SHELL: Small, turreted, ovate-conic or oblong-conic, rather 

 solid; periostracum light yellowish-horn, sometimes darker; surface 

 shining, lines of growth close-set, conspicuous; spiral striation absent 

 or only very slightly developed; nuclear whorls 1% in number, light 

 horn colored ; in outline the first whorl is very small, while the second 

 is very large, flattened, wide, and convex; the sculpture is minutely 

 substriate under a very high power but appears of a satin finish char- 

 acter under a low power (pi. XLIX, fig. D) ; whorls 5-6, convex, 

 roundly inflated, roundly shouldered above, gradually increasing in 

 diameter; body whorl occupying about half the length of the shell, 

 somewhat ventricose ; spire conic, turreted, more or less acute ; sutures 



^nly a few references, chiefly from American sources, are included above. 

 European citations would occupy several pages. 



