Specimens of monodon ulicie from the original locality of 
the same diameter are 34 mm greater in height. The gene- 
ral effect of the Michigan specimens is that of a depressed 
shell rather than that of a globular one as given by the true 
alicia. While this form seems to be sufficiently distinct both 
from the type and the var. alici@, yet in view of the small 
number of specimens and the indefinite locality it does not seem 
desirable to separate it under a varietal name at present. 
20. PoLYGyRA LEAI (Ward). 
Generally distributed south of the Saginaw-Grand valley. 
Alpena is the only reported locality further north. ‘‘ Not 
abundant in Kent county,” Streng. 
21. STROBILOPS LABYRINTHICA (Say). 
Apparently one of the rarer species. Saginaw, Kent, 
Kalamazoo and Berrien counties are the only localities 
reported. 
The recent revision of the species of this genus by Pils- 
bry render all the early records for this form unavailable 
except generically. I have accordingly cited for all the spe- 
cies of Strobilops only such localities as have been verified by 
personal examination of specimens. 
22. STROBILOPS VIRGO (Pils.) 
The only species of the genus represented in the northern 
part of the state, where it is quite common. South of Iosco 
county, the only localities reported are in Oakland, Saginaw 
and Kalamazoo counties. In the latter two, it was found 
associated with /aéyrinthica and in the first named with afinzs. 
23. STROBILOPS AFFINIS Pils. 
This is the most common species of the genus in the 
southern part of the state. It has not, as yet, been reported 
north of the Saginaw-Grand valley. In Kent county it was 
found associated with /ebyrinthica and in Oakland county with 
vvrgo. In Genessee, Macomb, Washtenaw and Lenawee coun- 
ties it was the only species represented. This form can easily 
be distinguished from z/rgo not only by its larger size and its 
“peculiar armature of numerous short lamella. extending ina 
forwardly curved series from the axis across the base and up 
the side wall” as stated by Pilsbry, but also by the constantly 
larger umbilicus at all stages of growth. In vz7go the umbili- 
cus is a mere perforation. Where for any reason the arrange- 
ment of the lamella or the parietal folds cannot be observed, 
16 
