358 THE CHICAGO ACADEMY OF SCIENCES. 



life zones, east of the Appalachian Mountains. It is characteristic of 

 the Carolinian region. Like many plants, it has extended its range 

 into southern New Jersey. 



RECORDS. 



New Jersey : Mouth of Woodbury Creek, and in tide meadow ditch at 

 Washington Park near Gloucester, Camden Co. (J. A. Allen). 



South Carolina: South Carolina (Gibbs; Say) ; Charleston, S. C. (Lewis; 

 Walker) ; Charleston, S. C, collected in 1865 in a low lot in Alexander Street 

 near Chapel, only four or five blocks from the center of the city (now filled up 

 and destroyed) ; Sullivan's Island, four miles from the city (Mazyck). 



Geological Range : Unknown. 



Ecology : In tide meadow ditch and at mouth of creek (Allen, 

 New Jersey) ; in vacant lots and in ditches (Mazyck, South Carolina). 



Remarks: Humilis may be known by its acute spire, convex 

 whorls, obese body whorl and narrow, somewhat triangular inner lip, 

 which is not notably apprcssed at its junction with the parietal wall 

 but forms an evenly rounded expansion. It greatly resembles umbili- 

 cata, but may be distinguished by the inner lip which, in umbilicata, 

 forms a broad, triangular excavated expansion reaching to the base 

 of the aperture, while in humilis the lower part of the inner lip is 

 turned upward and not backward. Humilis has also a mere obese 

 body whorl. The formation of the inner lip of the two species is 

 quite different and no difficulty will be encountered in distinguishing 

 the two forms if this point is observed. The shape of the inner lip 

 is also different in parva, sterkii and the other related species. 



Until recently Say's humilis was believed to be one of the best 

 known as well as one of the commonest of American Lymnseas. At 

 present it may be said to be one of the rarest and least known. Mr. 

 Bryant Walker was the first conchologist to call attention (in a letter 

 to the writer) to the relation of certain northern forms placed in 

 humilis to umbilicata, and also to the relation of modicella to humilis. 

 A careful study of all available material, including Say's types, follow- 

 ing Mr. Walker's suggestion, revealed the fact that typical humilis 

 was not authentically known outside of the region east of the Appa- 

 lachian Mountains. The fact also became apparent that modicella was 

 simply a northern form of humilis, thus, in part, corroborating Bin- 

 ney's opinion expressed in 1865. (See remarks under modicella.) 

 Some of the records of humilis from Louisiana, New Mexico and 

 Texas may have been founded on the true humilis, but in the new 

 aspect of the case it has seemed best to restrict the records to those 

 which are known to have been founded on Say's South Carolina form. 

 Special search should be carried on for this species, which may be 



