LYMX.EID.E OF NORTH AMERICA. 263 



elongate ovate, somewhat narrowed above ; peristome thin ; inner lip 

 narrow, reflexed over the umbilical region, rolled over and appressed 

 at the point of contact with the parietal wall, but standing more erect 

 at the lower part; umbilical chink small, narrow but distinct; axis as 

 in Galba hum His. 



Length. 



Breadth. 



Aperture length. 



Breadth. 





8.50 



4.25 



4.75 



2.75 mill. 



Say' 5 type 



8.50 



4.50 



4.00 



2.00 " 



jamesii 



7.75 



3.25 



4.50 



2.25 " 



Chicago 



7.00 



3.50 



4.50 



2.00 " 





8.50 



5.00 



5.00 



2.75 " 



Oakland Co., Mich. 



7.00 



4.00 



4.00 



2.00 " 



" " 



9.50 



4.90 



5.00 



3.00 - 



Macomb Co., Mich. 



8.25 



4.50 



4.50 



2.50 " 



'•' " 



12.00 



6.00 



5.30 



3.00 '•' 



Alpena, Mich. 



10.25 



5.00 



5.00 



2.75 " 





10.50 



5.75 



5.75 



3.00 " 



Hamilton Co., Ohio. 



Types : Modicella, Academy of Natural Sciences, Philadelphia, 

 two specimens, Xo. 58790; jamesii, one specimen, Smithsonian Insti- 

 tution, Xo. 29106. 



Type Locality : Owego, Tioga County, Xew York, on the Sus- 

 quehanna River, 1 for modicclla; ponds near Cincinnati, Ohio, for 

 jamesii. 



Animal : Similar externally to obrussa; color light brownish or 

 blackish, lighter on the foot. 



Jaw : Similar to that of obrussa. 



Radula: Formula : T5 lVfl44+T+f+i-H-V (25-1-2 5) ; lateral teeth 

 tricuspid; the seventh tooth transitional; marginals beginning abruptly 

 on the eighth tooth. The shape of the teeth do not differ from those 

 of obrussa and its varieties. 



Genitalia : Similar to those of obrussa. 



Range (Figure 25) : Eastern Quebec, Xova Scotia and Xew 

 Jersey west to Vancouver Island; Manitoba south to southern Cali- 

 fornia, Arizona, Texas and Alabama. 



Modicella is one of the most widely distributed of the smaller 

 Lymnseas, its range embracing practically the whole of the United 

 States, north and west of the Alleghany Mountains. It is, therefore, 

 found in the Boreal. Transition, and Upper and Lower Austral life 

 zones. It seems to be absent from the gulf strip of the Austro-riparian 

 division of the Lower Austral life zone, as well as from the Atlantic 

 Coast strip of the Lower Austral, its place here being taken by typical 



1 In Binney's monograph this locality is spelled Oswego. 



