318 THE CHICAGO ACADEMY OF SCIENCES. 



American Conchology. No specimens have been seen from this lo- 

 cality. When better understood, desidiosa will probably be found to 

 inhabit a much wider range than here indicated. 



RECORDS. 



Indiana: New Harmony, Posey Co. (Leseuer, Say). 



New York : Small stream under Erie Canal, Western Wide Waters, 

 Rochester, Monroe Co.; near Geneva, north end Seneca Lake, Ontario Co. 

 (Baker) ; Cayuga Lake; Falls of Niagara, Erie Co. (Say) ; Young's Quarry, 

 Williamsville, Erie Co. (Miss Walker). 



Pennsylvania: Pennsylvania (Say). 



Geological Distribution : Unknown. 



Ecology: Dead specimens were found along a marshy reed- 

 bordered shore in Seneca Lake ; Miss Walker found it in an old quarry 

 at Williamsville. 



Remarks: An examination of Say's specimens of desidiosa in 

 the Academy of Natural Sciences of Philadelphia reveals the fact that 

 all subsequent naturalists have misunderstood this species and have 

 given the name to a species belonging to a different group of Lymnaeas. 

 The true desidiosa is a member of the palustris group, as shown by 

 Say's specimens and by a close study of Say's description and figures. 

 The two specimens in the Philadelphia Academy may be described as 

 follows i 1 



Shell oblong-ovate, rather solid, color pale horn ; surface dull, lines 

 of growth crowded, conspicuous, crossed by impressed spiral lines ; 

 whorls 5^, convex; the body whorl is quite convex; spire acutely 

 conic, about as long as the aperture ; sutures well impressed ; apex of 

 V/2 whorls, brownish horn; aperture long-ovate; outer lip thin, with 

 an internal rib or varix; inner lip reflected over and appressed to the 

 parietal wall, leaving a small umbilical chink; columellar axis with a 

 distinct, thick plait. 



Length. Breadth. Aperture length. Breadth. 



15.00 7.50 8.00 3.00 mill. 



14.25 7.50 7.75 3.50 " 



The specimens bear the following label in the original handwriting : 

 Lymnea desidiosa Say. Journ. Acad. V. 2, p. 169. T. Say, Penn. ? 

 (No. 58731.) 



The figure in Binney (fig. 68) is said to be from an authentic 

 specimen in the Philadelphia Academy, but no such specimen is now 

 in existence, nor are the specimens mentioned from Cayuga Lake to 

 be found. In the absence of any other authentic material, it would 

 seem that Say's specimens must be taken as typical of desidiosa. A 



'The specimens are somewhat narrower than Say's figures in Amer. Conch. 



