_— 
ce 
CO 
THE CHICAGO ACADEMY OF SCIENCES. 
Penis- 
Penis- Rec.sem. Prostate Vas. sac 
Penis. sac. duct. duct. def. retractor. Shell. Locality. 
2.00 7.50 6.50 10.00 28.00 2:25 34.00 Sault St. Marie. 
2.00 6.50 6.50 8.00 30,00 2.25 33.00 a $ uy 
2.00 6.50 6.50 6.50 29.00 2.25 28.00 poet rf 
2.00 8.00 12.50 28.00 78.00 9.00 50.00 Siskowit Lake. 
2.00 9.00 12.00 26.00 75.00 8.50 45.50 oe = 
It will be noted that there is a marked difference in the compara- 
tive lengths of the vas deferens and the prostate duct between the 
Sault St. Marie and the Siskowit Lake specimens. This may be ac- 
counted for by the size, the latter individuals being a third larger than 
the former. 

Init, aly 
RANGE: (Figure 12) Northern Michigan and Lake Superior. It 
has not been found outside of the area of Lake Superior and the 
northern part of Lake Michigan. It is probably peculiar to the great 
iakes and hence an inhabitant of the Canadian region and life zone. 
