LYMNEIDA OF NORTH AMERICA. 155 
RANGE: Michigan to Minnesota north of the 45th parallel of 
north latitude. A species of the Canadian and Upper Mississippian re- 
gions and of the Canadian and Transition life zones. 
: RECORDS. 
MicuHicGaAn: Isle Royale; various localities (Adams; Gleason; Walker). 
Minnesota: Lake Harriet, near Minneapolis, Hennepin Co. (Daniels). 
WIsconsIN: Quynoch Point, Eagle Bay, and other portions of Tomahawk 
Lake, Oneida Co. (Baker). 
GEOLOGICAL RANGE: Unknown, 
Ecotocy: Lilliane is typically an inhabitant of sandy shores, in 
shallow water, where it is subjected to heavy wave action; only once 
was a specimen found in a still-water habitat, and this instance was 
undoubtedly caused by drifting from its normal habitat. When any 
number of specimens were found, the habitat was invariably an ex- 
posed beach. Associated with lilliane were Galba emarginata wiscon- 
sinensis and Planorbis binneyt. Individuals were observed crawling 
over the sandy beach or attached to water-soaked logs or other shore 
debris. The animal of this race exhibits two color modifications, one 
bright yellow and the other black or grayish-black. No cause for this 
color dimorphism was apparent. It is not protective, as both forms 
occupy the same area of white sandy beach. See the introduction, 
(page 45) for a discussion of the breeding habits of this race. 
Remarks: Lilliane may be known by its short spire, long and 
narrow aperture, and compressed body-whorl. It was at first thought 
to be a form of sanctemarie but a comparison with that species shows 
it to be uniformly narrower with compressed body-whorl, and more 
acute spire. In sanctemarie the body-whorl is usually very rotund ; 
the aperture is also roundly ovate, while in lilliane it 1s elongate-ovate. 
The musculature of the male organ is also quite different from sanc- 
temarie, and similar to that of appressa. Lilliane differs from ap- 
pressa in its short spire, flattened and compressed body-whorl and elon- 
gated aperture. It appears to be a distinguishable race of stagnalis. 
No true appressa were found associated with this race in Tomahawk 
Lake. There were a few specimens with spires and aperture of equal 
length, showing clearly that the race is a modification of the appressa 
type, caused, doubtless, by a change of environment. 
At Isle Royale, in Lake Superior, a form of stagnalis occurs which 
at first sight appears quite distinct. A number of individuals, how- 
ever, approach very closely to var. lillian@ and they may be referred 
provisionally to this race. Judging from the material at hand, this 
is a transition form between appressa and lilliane, representing, per- 
haps, one of the stages in the evolution of the race. The Isle Royale 
