THE NAUTILUS. 



of the same genus which may be new. Also a small white Pliysa 

 which is provisionally referred to P.gyrina Say. A small elongated 

 Limncea of the reflexa group from the same locality, seems to be 

 the L. laneeata Old. No less than seven different species of Lim- 

 ntcidae, six of operculates, and many Pisidia were brought up by 

 one haul of the trawl from this prolific locality. In a small lake 

 near the south end of Beaver Island, which was simply swarming 

 with animal life, were found the finest specimens of Limmm HIIIJI/H 

 Migh. yet seen from Michigan. The largest example collected 

 measured 28J mm. in length and 19 mm. in breadth, the aperture 

 being 19 i mm. long and 13 mm. broad. 



The Limnceidae of Pine Lake, which empties into Lake Michigan 

 at Charlevoix, were also extremely interesting. The bottom of the 

 lake is composed almost wholly of marl, except where it has been 

 covered by a thin coating of sand washed in from the shores, and, 

 as a consequence, both plant and animal life exist under very un- 

 favorable circumstances. The level of the lake seems to have been 

 lowered by the canal made by the U. S. Government to connect it 

 with Lake Michigan, and the former lake terrace is now largely ex- 

 posed, and, in many places, quite dry. In the numerous pools, how- 

 ever, which are left along the shore, the Limncea cataseojihnn Say is 

 found in great abundance and almost infinite variety. It varies in 

 shape from the comparatively slender form usually found in the 

 Great Lakes to the globose form described as L. pinguis by Say, and 

 seems, in many cases, to run very close to that of L. ample Migh. 

 The Pine Lake examples have usually a very thick, solid opaque 

 shell, and a large proportion are more or less distorted, the most 

 common effect of their unfavorable environment being apparently 

 to induce a very abrupt and rapid expansion of the outer lip, which, 

 in most cases, is accompanied by a heavy callous deposit all round 

 the aperture. The dredge also brought up from the marl of the 

 bottom some other curiously distorted forms of Limmm, whose 

 specific position has not yet been satisfactorily determined. The 

 curious Planorbis mitltii'olvis Case also occurred here, rarely alive, 

 but in great abundance among the dead shells along the shore. 

 There is reason to suppose that these shells came largely from the 

 marl deposits under the lake. It also seems probable that this 

 species will prove to be only a form of P. campanttlatus Say, pecu- 

 liar to localities where the marl is found. At any rate, all the lo- 

 calities in this State, from which it is now known, are alike in this 



