268 



THE CHICAGO ACADEMY OF SCIENCES. 



Smithsonian collection, is a form of modicella. The cotype has a 

 narrow reflection of the inner lip which leaves a rather small umbilical 

 chink. A comparison of the figure on plate XXXI, which is a photo- 

 graph of the cotype, with Tryon's figure 3, plate 18, of his continu- 

 ation of Haldeman's Monograph, will serve to show how little depend- 

 ence can be placed upon a figure made by the ordinary artist in correctly 

 depicting the shells of mollusks. 



Galba humilis rustica (Lea). Plate XXXI, figures 10-14. 



Lymnca rustica LEA, Proc. Amer. Phil. Soc., II, p. 33, 1841; Trans. Amer. 

 Phil. Soc., IX, p. 10, 1844; Obs., IV, p. 10, 1848. SCUDDER, Bull. Nat. Mus., 23, 

 pp. 33, 44, 201, 1885. 



Lymnaa rustica WHEATLEY, Cat. Sh. U. S., p. 23, 1843. 



Limntsa rustica BINNEY, Check List, p. 12, 1860; L. & F.-W. Sh. N. A., 

 II, p. 65, fig. 106, 1865. CLESSIN, Mai. Blatt, n. s., Ill, p. 81, 1881. CKLL., Ann. 

 Mag. N. H., Ser. 5, XIX, p. 176, 1887. 



SHELL : Small, elongated, subfusiform ; periostracum light yellow- 

 ish horn, darker in some specimens ; surface shining, growth lines 

 coarse, spiral lines absent or very faint; whorls 5 to 5^, convex, rather 

 slowly increasing in diameter, the body whorl suddenly enlarging; 

 spire long, very acute, generally a trifle longer than the aperture ; 

 nuclear whorls resembling those of modicella; sutures impressed ; 

 aperture usually narrowly elliptical; outer lip thin, sometimes with a 

 varix ; inner lip narrow, reflected, the lower part turned up, the upper 

 part at its junction with the parietal wall impressed and flattened, 

 forming a slight plait; umbilical chink usually very narrow, in some 

 specimens nearly closed ; axis as in modicella. 



Breadth. Aperture length. 



Breadth. 



1.50 mill. Smithsonian specimen 

 2.10 

 2.00 

 2.50 



2.50 " 

 2.00 " " 



Joliet, 111; 



Mohawk, N. Y. 



(c te 



Albuquerque, N. M. 



Length. 



7.50 4.00 3.75 



8.75 4.00 4.50 



8.50 4.00 4.00 



9.75 4.50 5.00 



10.50 4.75 5.50 



8.50 4.00 4.00 



7.75 4.00 4.00 2.00 



8.50 4.25 4.50 2.25 



9.75 4.75 4.90 2.25 



9.00 4.00 4.00 2.50 



10.00 4.80 4.50 2.50 " 



TYPES : Not in existence ; autotype, one specimen, Smith. Inst., 

 No. 118652. 



TYPE LOCALITY: Poland, Ohio. 



ANIMAL : Not differing externally from modicella. 



JAW : As in modicella. 



Alpena, Mich. 

 Cedar Lake, Mich. 



