^ength. 



Width. 



24.00 



8.00 



23.00 



7.75 



22.00 



7.00 



THE CHICAGO ACADEMY OF SCIENCES. 



Shell: Attenuated, more or less scalar, periostracum light yet 

 lowish horn; sculpture as in palustris; whorls 6 to 7, loosely coiled, 

 generally quite convex ; spire long, attenuated, pointed, somewhat 

 scalar; sutures typically very deeply impressed; aperture elongate- 

 ovate or lunate, about one-third the length of the shell ; peristome thin, 

 bordered by a heavy varix which is edged with dark red or chestnut; 

 inner lip thin, narrow, reflected over and nearly closing the umbilicus, 

 leaving a very small chink; columella with a distinct, ascending plait; 

 axis strongly twisted. The surface is sometimes malleated. 

 Aperture length. Width. 



9.50 5.25 mill. Joliet, 111. Type 



9.00 5.00 •' 



8.75 4.75 " 



Types : Chicago Academy of Sciences, four specimens, Xo. 23606 ; 

 cotypes, Academy of Xatural Sciences, Philadelphia. Xo. 8155. . 



Type Locality : Rock Run, Joliet, Illinois. 



Animal : Xot differing from typical palustris. 



Jaw : As in palustris. 



Radula (PI. VIII, fig. G ) : Formula 4 -A+l +f +i+f +f + 4 -V 

 {32-1-32) ; the teeth do not differ materially from those of palustris; 

 the transition teeth begin at the ninth tooth and the marginal teeth 

 begin at the eleventh tooth. There are over eighty rows of teeth. 

 The intermediate teeth sometimes begin at the tenth tooth. 



Genitalia : In all respects like those of typical palustris. The 

 retractors of the male organ vary slightly in size, but otherwise the 

 organs are very uniform. (PI. XV, fig. G.) 



Several dissections gave the following result (dissection Xo. 23597 

 and Xo. 23617), which is markedly uniform: 



Ret. Ret. 



penis-sac. Rec. sem. 

 1.00 4.00 



1.25 4.00 



1.50 4.00 



Raxge (Figure 36) : Southern Wisconsin to eastern Xew York; 

 central Michigan south to northern Illinois and northern Ohio. 



Jolictcusis occupies an area along the borders of the humid divi- 

 sions of the Transition and Upper Austral life zones. It appears to 

 be typical of the drainage of the Great Lakes, being confined to the 

 area bordering the Canadian and Upper Mississippian regions. 



RECORDS. 



VXITED STATES. 



Illinois: Rock Run, Joliet, Will Co. (Ferriss) : Berry Lake, Cook Co. 

 (Higley) ; south of Wolf Lake, Cook Co. ("Jensen"): Elgin. Kane Co.; Crystal 

 Lake, McHenry Co. (Xason). 



Penis. 



Penis-sac. 



penis 



2,50 



2.10 



2.00 



2.60 



2.10 



1.25 



2.60 



2.10 



1.50 



Prost. 

 duct. 



Vas. def. 



Shell. 



5.00 



13.25 



19.00 



5.00 



13.00 



19.00 



5.00 



14.50 



19.00 



