LYMNZIDZ OF NORTH AMERICA. 319 
close analysis of Say’s description would seem to indicate that he did 
not have the shell before him which has so long borne the name of 
desidiosa. He says! (italics the author's): “Jt is closely allied to 
clodes, but the whorls are more convex, one less in number, and the 
two terminal ones are proportionately smaller.” This statement is 
repeated in the American Conchology. This comparison with elodes 
would scarcely have been made by Say, who possessed a peculiarly 
discriminating sense of minute differences between shells, if he had 
been describing the shell historically known as desidiosa. The size of 
the Philadelphia specimens (15 mill.) also corresponds pretty well with 
the size given by Say (7/10 of an inch=about 17 mill.) The most 
convincing fact to the writer is the presence of a specimen of “desidi- 
osa@’ (authors) in the Philadelphia Academy marked “Lymnea...... : 
Canandaigua Lake. T. Say” (No. 58732), showing that the form 
usually called desidiosa is not the one so called by Say. Prof. Edward 
S. Morse, who made the drawings for Binney’s work, has been unable 
to add to our knowledge concerning the specimen figured by Binney. 
During the summer of 1907 the writer made three trips to Cayuga 
Lake, one to the south end at Ithaca, and two to the north end at the 
town of Cayuga, with the hope of securing specimens which would 
correspond with Say’s specimens. Three whole days were spent in 
exploring several miles of the shore and the small creeks, and while 
specimens of both palustris and obrussa were obtained, not a single 
specimen was found which agreed with Say’s desidiosa. The palustris 
were the large, thin-shelled form and the obrussa were rather small 
specimens, not at all like the description or specimens of desidiosa. 
As Say gave no particular part of Cayuga Lake as the identical spot 
in which the types were collected, it renders the task of finding loco- 
types well nigh impossible, since the lake is thirty-eight miles in length. 
Recently, Miss Mary Walker, of Buffalo, New York, sent the 
writer a number of shells from Young’s Quarry, Williamsville, New 
York, which are identical with Say’s specimens of desidiosa, having 
the same number of whorls and almost the same measurements. These 
are given for comparison. 
Length. Breadth. Aperture length. Breadth. 
15.00 7.50 8.00 3.00 mill. Say’s specimens 
14.25 7.50 ho Sato) ~ 3 
15.00 8.00 8.00 AL00I ss Miss Walker’s 
14.00 8.00 8.00 3:50) re aH 
Say’s figure in the American Conchology (plate 55, fig. 3) corre- 
sponds with the specimens from Williamsville, all having the peculiar 
1Journ. Acad. Nat. Sci., II, p. 169. 
