34 THE NAUTILUS. 



L. emarglnata Say. A very abundant species through the north- 

 ern part of the state and of great variety. Its most characteristic feat- 

 ure being a thick heavy shell, usually pure white and usually quite 

 opaque, sometimes translucent. Specimens from Higgins Lake, 

 Roscommon County, exhibit great variety in the form of the aper- 

 ture which is frequently much expanded. Specimens from Sault 

 St. Marie approach very close to Haldeman's figures of his L. ser- 

 rata (Mon. pi. 2, fig. 6-8). 



L. catascopium Say. An abundant and characteristic species of 

 the Great Lakes, and their connecting rivers. Specimens from the 

 north acquire the thick solid shell so common in emarginata. 



L. caperata Say. Cited by Miles, Currier, Smith and De Camp. 



L. cubensis Pfr. This form, hitherto known as L. umhUicata 

 Ads., has a range over the whole of the State. 



L. pallida Ad. Cited by Miles, Currier and De Camp. 



L. desidiosa Say. Very common everywhere. 



L. huviilis Say. Very common and variable. 



L. galbana Say (?) The form thus doubtfully designated, if not 

 the living representative of Say's fossil species, has never been 

 described. It has been found in Emmet, Grand Traverse, Alpena 

 and Oakland Counties, and would thus seem to have a wide range 

 through the state. It is a Avell marked form and seems to be sub- 

 ject to less variation than is usual in this genus. 



L. bulimoides Lea. Cited by De Camp, " found in greenhouse, 

 probably introduced by plants." 



L. gracilis Jay. Reed's Lake, Kent County, is the only Michi- 

 gan locality known for this species. 



Physa lordi Baird. Northern part of the state. P. parkeri 

 Currier, from Houghton Lake, is generally considered a synonym. 



P. ancillaria Say. Generally distributed over the State, and 

 exhibits a great degree of variability. 



P. sayi Tapp. Very common. Cited by Currier and De Camp 

 as var. Warreniana Lea. Specimens from a small pond near 

 Traverse City, collected by Dr. Leach, are remarkable for the ten- 

 uity of the shell and the expansion of the outer lip. In some 

 instances the newly formed lip was so thin as to be completely 

 reflected back on the outside of the shell. Whether the local influ- 

 ences in this case were similar to those which, according to Prof 

 E. S. Morse, produced the Physa fragilis Mighels I cannot tell ; 

 but the two forms would seem to be identical. 



