A Monograph of the Species of Pisidium. 361 
bridge, Vt. (Adams.) Cambridge, Mass., (Stimpson.) Gro- 
ton, Mass. (Lewis.) Conn. (Linsley.) Manhattan Island, N. Y. 
(Nobis.) Lake George and Canandaigua Lake, N. Y. (No- 
bis.) Herkimer, N. Y. (Lewis.) 
Osservations. Compared to the P. dubium, this species 
is less oblique, transversely shorter; the margins are more 
rounded, the striations are less heavy, the color is different, 
and the whole shell is smaller and more delicate. Its foreign 
analogue is the P. australe of Pfeiffer. 
This shell was discovered by Dr. Mighels and Prof. Adams, 
among some dead leaves in a swamp near Weybridge, Vt. 
It lives in swamps, and buries itself in the mud. Prof. Ad- 
ams has observed its occurrence under stones. I have fre- 
quently found it in running streams in company with P. vari- 
abile and P. compressum. The animal is very lively. 
fF Ns 
19. Prsrprum Kurz Nobis. 
Cabinet of the B. S. N. H. 
PL XII. Fig. 5, 6, 7. 
Pisidium Kurtzii Nobis. Bost. S. N. H. Proc. iv. 162. 
Descriptioy. Shell very small, subovate, rather equilate- 
ral; margins rounded ; beaks but very little removed from 
the centre, large, obtuse at the summit, approximate ; stria- 
"ons very fine; color pale yellow; hinge margin rather 
Straight ; teeth rudimentary. 
imensions, Long. 0.12 ; lat. 0.09 ; diam. 0.075 inches. 
EOGRAPHICAL DrsrRIBUTION. Charleston, S. C. (Kurtz.) 
OnsEnvaTIONS. This species is without doubt the smallest 
JOURNAL B. s, N. H. 47 JUNE, 1852. 
