334 
isfactory protection. Extensive chemical con- 
trol methods in rocky or dense terrain would 
probably be of only temporary value unless 
new and more specific chemicals could be 
developed. The developments in new chem- 
icals would probably have to be a divergence 
from related aldehydes, as was shown by the 
work of Lange (1941:321) in which chem- 
icals related to metaldehyde were found to 
have no attraction for slugs and the European 
brown snail. 
Cultural methods had definite value. Clear- 
ing dense underbrush near gardens or field 
plantings was found to be of value, as was 
the elimination of piles of refuse or other 
places where snails could hide during the day. 
The work of Dr. F. X. Williams in Africa, 
reported by Mead (1949:41), revealed two 
predatory snails ( Gonaxis sp. and Edentulina 
sp.) which may prove of value, but they re- 
quire special investigation before they can be 
liberated. Most terrestrial predatory snails, 
unless they have a reproductive potential 
greater than Achatina or a decided specificity 
for Achatina , probably would not be entirely 
satisfactory in reducing large populations of 
the giant snail. This conclusion would also 
apply to the large predacious carabid beetle, 
Tefflus sp., found by Dr. Williams in Africa. 
OTHER TERRESTRIAL SNAILS 
In a control program it is necessary to rec- 
ognize other terrestrial or fresh-water mob 
lusks present in an area, and to know their 
distribution and ecological relationships. A 
complete survey was not made, but the fol- 
lowing list shows present knowledge con- 
cerning these other species found in the 
Marianas Islands: 
LOCALITY 
AND DATE DRTER- 
COLLECTED SPECIES MINER 
Magicienne Bay, 
March 18, Lymnaea (Fossa- 
1948 via) ollula Abbott 
PACIFIC SCIENCE, Vol IV, October, 1950 
Loa Loa, March 
1 1—12, 1948 
Lamprocystis sp. 
Omphalotropis 
Lange 
cookei 
Omphalotropis 
Lange 
evosa 
Omphalotropis 
Kondo 
suhmaritima 
Kondo 
Fythia 
intermedia ? j 
Kondo 
Subulina octona 
Kondo 
Succinea sp. 
Truncatella 
Kondo 
querini 
Kondo 
Mt. Nafutan, 
March 12, 
Gastrocopta 
Abbott and 
1948 
lyonsiana 
Lamellaxis 
Kondo 
gracilis 
Lamprocystis 
Abbott 
misella 
Omphalotropis 
Kondo 
conica 
Kondo 
Omphalotropis 
cookei (type 
locality, Abbott, 
1949:263-66) Abbott 
Omphalotropis 
erosa 
Kondo 
Fythia sp. 
Succinea 
Kondo 
piratmum ? 
Kondo 
Succinea sp. 
Synopeas 
Kondo 
javanicum ? 
Truncatella 
Kondo 
querini 
Kondo 
Marpi Point, 
March 4, 1948 
Diplommatina 
Abbott and 
taeneolata 
Georissa 
Kondo 
biangulata 
Abbott 
Lamprocystis sp. 
Nesopupa 
Abbott 
quadrasi 
Omphalotropis 
Kondo 
erosa 
Omphalotropis 
Kondo 
suhmaritima 
Paludinella 
Abbott 
conica 
Abbott 
Partula gibba 
Abbott and 
Kondo 
Succinea sp. 
Abbott 
Marpi Point, 
March 18, 
Lamellaxis sp. 
Lange 
1948 
Omphalotropis 
cookei 
Omphalotropis 
Lange 
sp. 
Lange 
