LIMNuSlA. 



ST 



" The L. macrostoma which I s-eud you requires a note. It 

 comes as near a case of spontaneous generation as anything 

 within my observation. It was found in a little pool about twenty 

 feet in diameter, entirely cut off from streams and fed by a spring. 

 I had for years frequented it for Desmidia, &c., in which it was 

 very rich. One season, and one only, appeared these Limnsese 

 which do not occur elsewhere, as far as I now know, within twenty 

 miles. The pond dried up that season and destroyed the iQcality." 



Fig. 46. 



Subgenus BULIMNEA, Hald. 



Shell thick in texture, ovate, inflated ; spire short, outer lip 

 not expanded. 



Liimiaca megasoma, Say. — Large, dilated suboval ; spire short, 

 rapidly dimiuishing, acute ; whirls about five, rounded, obtusely wrinkled 

 across ; body whirl large, the wrinkles very 

 obvious, suture deeply impressed ; aperture 

 subovate, much longer than the spire, within, 

 chestnut-brown ; columella white. Length more 

 than one and six-tenths of an inch ; greatest 

 diameter one inch. 



This remarkably large and fine species was 

 found in Bois Blanc Lake, Northwest Territory, 

 by Dr. Bigsby, to whom I am indebted for 

 specimens. The color is brownish, sometimes 

 lineated across the body whirl with dull green- 

 ish and pale ochraceous ; and the chestnut- 

 brown color of the interior of the shell, com- 

 bined with its large dimensions, distinguish 

 this species from all others yet discovered in 

 this country. (Say.^ 



I.imnseus megasomus, Say, Long's Exp. II, 263, pi. xv, f. 10 (1824) ; 

 Binney's ed. 129, pL Ixxiv, f. 10.— KiJSTER in Ch. ed. 2, 36, pi. vi, 

 f. 20, 21. 



Limncea me.gnsomn. 



