438 THE CHICAGO ACADEMY OF SCIENCES. 



forms, besides occupying a wholly different drainage area. It is one 

 of the handsomest of the American Lymnaeas. 



Galba oronensis (Baker). Plate XLVII, figures 1-9. 



Limnaa emarginata BAKER, Bull. Chi. Acad. Sci., II, pi. I, fig. B, 1900. 

 NYLANDER, Nautilus, XII, p. 104, 1900 (part) ; Distr., Lim. emarginata, p. 4, 

 1901 (part). 



Lymnaa decollate, LERMOND, Shells of Maine, p. 38, 1908 (part). 



Radix decollata HERON, Ottawa Nat., I, p. 39, 1880. 



Lymncea decollata oronoensis BAKER, Nautilus, XVIII, p. 62, Oct., 1904. 

 LERMOND, Shells of Maine, p. 38, 1908. 



SHELL: Globose, inflated, solid; periostracum rich greenish horn 

 or dark olivaceous, inclining to black in some specimens ; surface shin- 

 ing, the growth lines somewhat elevated, sometimes producing indis- 

 tinct, fine elevations; spiral sculpture of fine impressed lines, giving 

 the surface a wavy appearance ; nuclear whorls rounded, smooth, very 

 dark horn colored, in outline resembling those of emarginata; whorls 

 l /2 to 5; very convex, the body whorl almost globular, sometimes a 

 little shouldered near the suture; spire broadly conic, depressed in 

 some specimens; sutures impressed; aperture roundly ovate, produced 

 anteriorly, occupying about two-thirds the length of the shell; it 

 is somewhat narrowed at the posterior end ; peristome thin and sharp ; 

 in old specimens the outer lip thickens within and forms a distinct 

 varix; inner lip tightly appressed to the parietal wall where it forms 

 a spreading callus; the umbilicus is either completely closed or (rarely) 

 there is a very narrow chink ; axis strongly twisted, forming a distinct, 

 ascending plait ; the interior of the aperture is brownish-red. 



Type. 



Caribou, Maine. 



TYPES: Collection, Bryant Walker, twelve specimens, No. 7912; 

 cotype, Chicago Academy of- Sciences, one specimen, No. 23784. 



TYPE LOCALITY : Orono, Penobscot Co., Maine. 



RADULA: Formula: /_V+*-i+t+i+i+*-*+T-T (36-1-36) ; the 

 teeth are similar in shape to those of catascopium and emarginata, dif- 

 fering principally in the number of laterals, which are nine in the 

 former and ten in the latter, while they number but eight in oronensis. 

 The large number of transition teeth (six) in oronensis is noteworthy, 

 there being but two in emarginata and four in catascopium. Laterals 



