64 rilE XAUTILUS, 



M. marglnata Say. Common in the southern part of the State. 

 The range toward the north of many of the species commonly met 

 with in the lower portion of the State is quite unknown, and to be 

 determined with any degree of accuracy will require a large amount 

 of extensive and careful field work. 



M. rngosa Bar. Common all over the lower peninsula, and some- 

 times attains considerable size. Detroit river specimens are smaller 

 and thicker than those from the warmer waters of the interior of the 

 State. 



31. undulata Say. Cited by Sager, and, no doubt, erroneously. 



Anodonta Benedidii Lea. Generally distributed. In the south- 

 ern part of the State it often attains considerable size. Detroit river 

 specimens as usual are smaller than the average. 



A. corpulenta Coop. Cited by De Camp from Berlin, Ottawa 

 county. Immature specimens from the Canal, at Grand Rapids, 

 are referred to this species by Mr. W. B. Marshall. 



A. decora Lea. A. inornata Anth., described from specimens 

 from Slawsou's Lake, Michigan, is referred to this species by Dr. 

 Lea. Cited as J., mornata hy Currier and De Camp; otherwise 

 does not appear to have been found in the State. 



A. edentula Say. Common everywhere and exceedingly variable 

 in size, shape and color. 



A. edentula rhoinbica Anth. This form, described by Anthony, 

 is entitled to varietal rank ; but can be too easily connected with 

 the typical form to be considered specifically distinct. 



A.ferruginea Lea. Cited by De Camp from the upper peninsula. 



A. Ferussaciana Lea. Cited by Sager, Miles, Currier and De 

 Camp. 



A. Footiana Lea. Abundant everywhere and in great variety of 

 form. ^1. McNielii of Anthony is considered synonymous by Lea, 



A. fluviatilis Dillw. Cited by Miles ; also by Sager and Miles, as 

 A. cataracta Say. Cited by De Camp from Pentwater, and as A. 

 cataracta Say, from the Grand river. 



A. Footiana opalina Anth. A most beautiful form, well entitled 

 to distinction as a color variety. 



A. fragilis Lam. A very common species and in some of its 

 many varieties one of our most beautiful ones. A. jiava, glandidosa, 

 imbricata, irisans and ji^dlida of Anthony and A. subcarinata of 

 Currier are considered as synonyms by Lea. I have no doubt but 

 that some, at least, of these forms are entitled to varietal rank ; but 



