4 University of Michigan 



9. Siiccikea retnsa Lea. Two very distinct forms of this 

 species were found on Charity Island : 



A. About typical, with a short spire, the largest specimen 

 measuring 11.5 mm. in length, aperture 8.5 and spire 3. 



B. Larger, more elongated and very obliquely coiled. The 

 largest specimen measures 16 mm. in length, the aperture 

 being 9.5 and the spire 6.5. This is evidently the same race 

 that has been recorded from Saginaw (Naut. vii, p. 127), but 

 it does not apparently attain the same size, as tlie rraginaw 

 shells reach 19.75 "'"''''• '" length, a ditl'erence of nearly 25%. 



10. Lymncra einayginata Say. A few specimens from 

 Charity Island are fairly typical of the lake form-'as found so 

 abimdantly at Mackinac Island, but most of the specimens 

 belong rather with the following variety. 



loa. Lymncra emarginata ontarioensis Muhlfeldt. Abund- 

 ant on the west beach of Charity Island and also on Little 

 Charity. This is one of the characteristic species of the 

 beaches here, as it is all along the Lake Huron shore north to 

 Mackinac City. The large majority of the specimens have the 

 "flat-sided" upper whorls and slightly impressed suture char- 

 acteristic of the form, but there is a complete gradation into 

 the rounded whorls and deeper suture of the typical form. 



11. I.ynincca catascopiuui Say. A few specimens from 

 Charity Island seem referable to this species. 



12. Lyinufra refle.va Say. Apparently common on Charity 

 Island, but the exact locality was not given. Taken as a whole 

 the series seem to show that the island form is rather a small 

 one. The largest specimen collected measures 29.5 mm. in 

 length, but only an occasional shell exceeds 25 mm. in length 

 and most of them fall below that. 



T2a. Lyinncca refle.va walkcri Baker. A few specimens 

 occurred with the typical form. They are unusually slender 

 and quite small, even as compared with the average shell of 

 the series. 



13. fy\miura elodes Say. A considerable number of speci- 

 mens of this species were found in "dried-up water-holes" in 

 the interior of Charity Island. A decided tendency toward 



