18 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA 
FAUNA. 
There are no other animals in the Mariana Islands whose presence or activities 
influence the lives or numbers of Partule, so far as observation goes. The shells in 
some of the species and varieties are brightly colored and consequently are quite 
conspicuous against the green of the vegetation; others are dull in coloration and are 
less distinct. As the various kinds differ markedly in their relative local abundance, 
it might be supposed that some animal enemies, also varying in their frequency, 
could be held accountable for the observed conditions; but not a single fact was 
noted in Guam or in Saipan which indicated that the snails were eaten by some 
carnivorous animal. If this does occur, it must be so rare as to be negligible in 
relation to the distribution of the diverse color-types of the species in the Mariana 
Islands. 
Aside from the fruit-eating and insectivorous bats, no indigenous mammals 
occurred in the islands. Among the introduced species, only rats and mice might be 
enemies of the snails; but these animals frequent the settlements and plantations 
rather than the bush. While now and then in Tahiti a shell would be found that had 
been bitten by a rat, such specimens were never observed in the Mariana Islands, 
although Partule occurred in far greater relative abundance near the villages, where 
the rodents abound. Inland birds are few, and they are either insectivorous or 
frugivorous. A large lizard of the genus Varanus exists, which is an eater of birds 
and birds’ eggs. The smaller lizards of the genus Emoza are very abundant even in 
the forests, but they seem to subsist entirely upon insects. Invertebrates are neg- 
ligible in the present connection, unless, indeed, some of the lower parasites may 
prey upon the snails; if such is the case, the results would hardly be selective, in the 
sense that one color-variety would be more susceptible than another. 
