LYMN^EHXE OF NORTH AMERICA. 405 



rower, thinner, the aperture is generally more elongate, the spire is 

 narrower and more acute, and the columellar plait is heavier. The 

 aperture is also somewhat differently shaped. Catascopium adamsi ap- 

 proaches nearest to sumassi; it differs from this race in its rounder 

 whorls, more ovate aperture and more decided columellar plait. It 

 also occupies a widely separated area of the country. Sumassi dif- 

 fers from palustris in being lighter in color, with heavier sculpture, 

 narrower shell, and differently shaped columella. It has the spermaceti- 

 like color of the catascopium group and not the brown color of palus- 

 tris. Binney's figure 56 seems to be quite typical and accurately repre- 

 sents the two specimens from the British Museum but his figure 57 

 would seem to represent a different species, perhaps jacksonensis. 

 This figure (57) has been used by Dall and others as typical of sum- 

 assi, but it does not agree with the description nor the cotypes in the 

 British Museum. Compare figure 14, on plate XLI, with Binney's 

 figure 56. 



Many of the references to sumassi are based on narrow or fragile 

 forms of palustris. Dr. Ball's reference to Snake River, Idaho, prob- 

 ably is based on Galba jacksonensis^ which is a much wider shell than 

 sumassi. The Lake Washington, Seattle, specimens are a form of 

 palustris. Sumassi replaces catascopium on the Pacific slope and will 

 probably be found to be widely distributed in the northwest when its 

 characters are understood and this territory is more thoroughly ex- 

 plored. 



Galba jacksonensis (Baker). Plate XLII, figures 27-31. 



Lymnaa jacksonensis BAKER, Nautilus, XXI, p. 52, September, 1907. 



Lymncea catascopium var. sumassi DALL, Alaska Moll., p. 78, 1905 (part). 



fLimncea sumassi BINNEY, L. and F.-W. Sh., II, p. 43, fig. 57, 1865. 



SHELL : Ovately-f usiform, inflated, solid ; periostracum very dark 

 horn ; surface shining, lines of growth coarse, crossed by deeply in- 

 cised spiral lines sagrinating the surface; one or two rest periods are 

 cliscernable as longitudinal bands on the body whorl and spire ; nuclear 

 whorls 1J4, very dark chestnut colored, much flatter and wider than 

 those of catascopium (see plate XLIX, figure N) ; whorls 5^2, 

 rounded, rather rapidly increasing in size ; body whorl large, ovately- 

 inflated ; sutures well impressed ; spire about equal to the aperture in 

 length, broadly conical; aperture regularly elongate-ovate, narrowed at 

 both ends, somewhat effuse anteriorly; outer lip with a chestnut 

 bordered internal varix ; inner lip in the adult rather broadly re- 

 flected over the umbilicus, leaving a small, narrow chink; parietal cal- 



K^ompare figures 27 and 31 on plate XLII with Dall's figure 59. Also 

 compare these figures with the cotypes on plate XLI. 



