328 
PACIFIC SCIENCE, Vol. IV, October, 1950 
during a 2 -month period when I was in the breadfruit trees were pregnant. On Novem- 
field. The average weight increase was from her 11, 194-7, observations made in the same 
0.04 gram at hatching to 14.7 grams at the area showed that of several hundred exam- 
end of 156 days. This was an increase in ined only three were pregnant. Of hundreds 
weight of from 63 to 368 times above the of snails examined during the period from 
initial weight, depending upon the particular February 6, 1948, to April 4, 1948, no preg- 
snail involved. These rearings suggest that nant snails were found on Saipan. The loca- 
individuals vary greatly in their rate of tion of observations apparently influenced the 
grov/th, that weight can be lost when food relative percentages of pregnant snails, be- 
or water is withheld, and that whorls are cause, of several hundred snails examined on 
added regardless of the presence of adequate November 3, 1947, at Marpi Point, Saipan, 
food. Mature, pregnant snails were found in feeding on Operculina turpethum along a 
the field which were 2.25 to 3.5 inches long, roadway, not a single pregnant snail was 
having 7 to 7.5 whorls. found. Snails seeking sites for oviposition 
It was noted that under field conditions were found more frequently in more pro- 
there was a definite correlation between egg tected areas. 
laying and wet and dry periods. Egg laying Ordinarily there is a wet and a dry season 
occurred during the wet season. During the on Saipan, although this may not be marked 
dry season no eggs were laid and many snails inasmuch as rain can fall during any month, 
secreted brown to whitish epiphragms and There is also considerable variation, depend- 
became inactive. On October 28, 1947, eight ing upon where the observations are made, 
of the 50 snails examined in an area under The wet season is from July to November 
Fig. 5. Operculina turpethum, a preferred food plant of Achatina; Saipan, March 18, 1948. 
