478 LIMN^IDiE. 



Limnsea desidiosa. 



Fig. 150. 



Shell ovate-elongate, turreted; whorls five, convex, the upper ones very small; 

 suture deep ; aperture sub-ovate, longer than the spire ; sub-umbilicated. 



Liiniuvn desidiosa. Say, Journ. A. N. S. ii. 169 (1821); Lonf,^'s Exped. ii. 263 ; Am. 



Conch vi. pi. 50, fig-, 5; ed. Binn. 66, pi. 55, fig. 3. — Adams, Shells of Vermont, 



1.54 (1842).— Dk Kay, N. Y. Moll. 7.3, pi. 5, fig. 78 (1843). — Kuster, in Ciiemn. 



2d cd. 47, pi. 8, figs. 22-26 {Limncens). — Gould, Inv. of Mass. 219, fig. 150 (1841 ). 



— IIaldeman, Mon. p. 31, pi. 10; p. 48, pi. 13, figs. 16-18 (1842). — Anony. Can. 



Nat. ii. 198, fig. (1857). — W. G. Binney, Smith. Inst. L. and Fr. W. Shells ii. 48, 



figs. 68-73 (1865). 

 TJnimm acuta. Lea, Tr. Am. Phil. Soc. v. 114, pi. 19, fig. 81 (1837) ; Obs. i. 226. 

 Limnma obrussa, Say, J. A. N. Sc. v. 123 (1825) ; Binni^y's cd. 113. — De Kay, N. Y. 



Moll. 75 (1843). 

 Limiiceii philade/jAica, Lea, Proc. Am. Phil. Soc. ii. 32 (1841 ) ; Tr. ix. 8 (1844) ; Obs. 



iv. 8. 

 Limmmfusiformis, Lea, Pr. Am. Phil. Soc. ii. 33 (1841) ; Tr. ix. 10 (1844) ; Obs. iv. 10. 



Shell ovate, thin and fragile, the spire elongated and turreted ; 

 color a pale, dirty yellowish-green ; whorls five, very convex, and 

 for the most part suddenly contracted above, so as to pre- 

 sent a conspicuous shoulder; the two or three uppermost 

 whorls are very small, and the body whorl about seven 

 tenths the length of the whole shell ; surface generally dead, 

 and somewhat checked with irregular revolving and longi- 

 tudinal raised lines ; aperture large, usually three fifths the 

 length of the shell, oval, broadly and sub-equally rounded 

 both liehind and before ; the lip is considerably everted in front, 

 and along the left margin, where it is not closely appressed to the 

 whorl, and leaves a small, but evident umbilical opening ; callus 

 rather abundant ; fold on the pillar slight, and smoothly rounded. 

 Length, half an inch ; of aperture, three fifths of an inch ; breadth, 

 nine fortieths of an inch ; divergence, forty-five degrees. 



This species is found in most regions, about the muddy margins 

 of ponds and pools. From New England to Kansas. 



It is intermediate between L. elodes and L. himiilis. Its spire 

 is proportionally more slender, its suture deeper, its aperture pro- 

 portionally large and more oval, the fold of its columella much less 

 conspicuous, and it is a much more fragile shell than the former. 

 The latter, while it has the large, oval aperture, the deep suture 

 and shouldered whorls, is still more fragile, of a deep green color, 

 and is a short, inflated shell, with a much greater divergence of 



