276 THE CHICAGO ACADEMY OF SCIENCES. 



The animal of palustris is very rapid in movement. It 

 crawls out of the water and will remain in this position for a 

 long time. When crawling, the shell is frequently moved rap- 

 idly from side to side, and is carried at all conceivable angles. 

 It is a very rapid feeder and will soon clear up the sides of an 

 aquarium. Like other species of the genus, palustris has the 

 habit of rising very suddenly from the bottom to the top of the 

 water where it will then float shell downward. 



noa. Limniea palustris michiganensis Walker, pi. xxxii, fig. 5; pi. xxxi, 



fig. 25. 



Limnaa palustris michiganensis WALKER, The Nautilus, Vol. VI, p. 33, 

 pi. i, figs. 9, 10, 1892. 



This form is characterized by the aperture being about 

 one-half the total length, the outer lip is thickened within by a 

 bluish-white callus edged with brownish black; this shows as 

 a white longitudinal band on the outside of the shell; spire 

 acute, sutures impressed. Mr. Walker mentions very fine spiral 

 lines, but these are as fully developed in the typical forms as 

 in the variety. 



Length, 20.00; width, 8.00; aperture length, 9.00; width, 4.50 mill. (12083.) 

 " 17.00; " 7.00; " " 8.50; ' " 4.00 " (12083.) 



" 15.00; " 7.00; " " 8.00; " 4.00 " (12082.) 



Habitat: Associated with the type, but not as numerous 

 in individuals, and found from Michigan to Washington. 



nob. Limiuea palustris nutalliana Lea, pi. xxxi, fig. 6. 



Limncea nutalliana LEA, Proc. Amer. Phil. Soc., Vol. II, p. 33, 1841; 

 BINNEY, L. & Fr., Wat. Sh. N. A., p. 42, fig. 62, 1865. 



Several specimens apparently referable to this form (which 

 would appear to be a good variety of palustris} were collected 

 recently by Mr. J. H. Ferriss, at Rock Run, near Joliet. The 

 whorls in this species are more swollen and the sutures less 

 impressed than in typical palustris. The epidermis is also 

 peculiarly banded, the bands showing very plainly in the aper- 

 ture. It has been found only at the above locality. 

 Length, 20.00; width, 8.50; aperture length, 10.00; width, 5.00 mill. (12343.) 

 18.00; " 8.50; " " 9.50; " 5.00 " (12343.) 



Mr. Lea's description is appended for comparison. 



"Shell ovately conical, rather thin, striate, subdiaphanous, 

 pale brown, imperforate; spire rather short; apex red; sutures 

 impressed; whorls six, convex; aperture ovate, inflated; banded 

 within." 



The original specimens were from Oregon. 



