PARTULA CLARA. 73 
To account for the presence in Papenoo Valley of shells like those of the oppo- 
site side of the island, clearly different from var. marmorata of the eastern quadrant, 
two explanations suggest themselves. It is possible that Vaihiria snails might have 
been introduced into Papenoo upon vanilla cuttings; but the two valleys in question 
are far apart, and their native inhabitants do not have much intercourse because 
they belong to different tribal subdivisions formerly at enmity. Vanilla plants 
have been taken from Vaihiria to several valleys of Taiarapu, yet banded examples 
and the closely lined light shells of var. prima are entirely lacking in the peninsula. 
It does not seem probable that human agencies have been responsible for the intro- 
duction of the southern prima into the distant northern region of Papenoo. 
In the second place, migrants may have crossed the ridge which separates the 
upper portions of Vaihiria and Papenoo, where descendants may have worked their 
way down to the lowlands. A complete exploration of the great central basin of 
Papenoo would certainly prove or disprove this explanation, but in spite of all 
efforts, such a thorough investigation was impossible during the periods of field-work. 
The sharp difference between the shells in question and those of Faarumai, which 
are typical marmorata, together with the other circumstances noted, make the second 
interpretation more plausible than the assumption that human agency has trans- 
planted a southern form into a distant valley of the north. 
FECUNDITY. 
This species is similar to hyalina in the relatively large number of young and 
eggs present in the brood-pouch of a gravid individual. The egg-shell is also 
transparent, a condition that is not found in the remaining Tahitian species until 
the young snail is virtually ready to emerge. Anachronisms in the serial order of 
the embryonic individuals are nearly as rare as in hyalina; only two instances appear 
in the records. 
TaB Le 28.—Partula clara. Statistics of fecundity. 
: No. of | No. of Nos o: Per cent NOs OS || ASTER Average 
Region. ; gravid : young for 
stations.| records. > gravid. 3 for all. 
snails. and eggs.| gravid. 
Western quadrant.... 9 164 84 Hil 7 235 2.79 1.37 
Southern quadrant.... 18 277 235 84.8 910 3.87 3.28 
Eastern quadrant..... 7 31 22 70.9 79 3.59 3.51 
Maiarapuerraryeeieer 7 62 57 91.9 228 4.00 3.67 
INI So. bo suonido 41 534 398 74.5 1,452 3.64 Doth 
The statistics of fecundity are given in summary in table 28, comprising more 
than 500 records of snails belonging to the colonies of 41 valleys. The percentage of 
gravid individuals is far higher than in hyalina, but the average number of eggs and 
young is less, the figure being 3.75 per cent for hyalina and 3.64 for clara. Never- 
theless, the average for all individuals, 2.71 per cent, is higher than in the other 
species, 2.44 per cent. 
