140 
genetic mutation, though this seems unlikely 
for other considerations as well as the sugges- 
tion of non-bilaterality in the incurved cavities 
on tentacles 1 and 3. 
The possibility of this specimen representing 
a new species would seem very remote. At most 
it seems only to further accentuate the variability 
of this plastic genus. 
PACIFIC SCIENCE, Vol. XXII, January 1968 
REFERENCE 
Wong (Chi), Lois W., and Edward D. 
Wagner. 1956. Some effects of ultraviolet 
radiations on Oncomelania nosophora and 
Oncomelania quadrasi, snail intermediate 
hosts of Schistosoma japanicum. Trans. Am. 
Microscop. Soc. 75 : 204-2 10. 
