PARTULA OTAHEITANA. 233 
the proportions are not essentially diverse; (3) the greater development of the tooth 
in the dextral division, precisely as in Titaviri; (4) the consistent absence of the 
tooth in sinistral apex, again as in Titaviri and Apirimaue; (5) the smaller size of 
the phea class of both modes of coil. 
TasLe 177.—Partula otaheitana sinistrorsa. Tenaire Valley. 
MEAN VALUE. 
Shell. Aperture. Length aper- 
Series. No. GEES o- Laae Tooth, index. 
shell, propor- 
Length. Width. Proportions. Length. Width. Proportions. tions. 
mm. mm. p. ct. mm. mm. p.- ct. p. ct. 
apex, sin... .| 188 | 19.2149+ .0390) 10.6829 .0218) 55.5053 .1078) 9.8329 .0235| 7.4510 .0180) 75.6383 .1257| 51.2606 .0905) 1 
cestata, sin..| 106 | 19.0575 .0676) 10.6887 + .0320) 56.0943 +.1801| 9.8509+ .0335| 7.4849+.0264| 76.1226+.1818) 51.5943 .1441| 1.0734+.0191 
phea, sin....| 70 | 18.8728+.0938) 10.6657 .0396| 56.3571+.2103) 9.7600 .0440) 7.4343 + .0310} 76.2428 + .2060| 51.5571 .1341) 1.0435+.0165 
All, sin.....| 364 | 19.1033 .0338] 10.6813+.0162| 55.8406 .0874| 9.8242+.0180) 7.4522+.0136) 75.8956+.0932) 51.3599 .0688| 1.0296 .0065 
apex, dex...| 48 | 17.9313+.0907| 10.1292 + .0386) 56.5208 .2172| 9.2542+ .0384| 6.9334 .0204| 75.0834= .1945| 51.6041+.1723) 1.8776+.1042 
cestata, dex.| 120 | 17.9550+.0511) 10.0950 .0249) 56.1166+.1438) 9.2200+.0278) 6.9384 .0205) 75.1750 .1452} 51.2750+.1201) 2.0496+ .0663 
phea, dex...| 355 | 17.9520+.0297) 10.0927+.0147| 56.1648+.0815) 9.2488 .0164| 6.9530 .0129| 75.1028+.1000) 51.4295 + .0668) 2.2950=+ .0393 
All, dex. ...| 523 | 17.9508+.0248| 10.0965+.0120) 56.1864 .0676| (9.2426 .0133) 6.9478 .0104| 75.1176+.0777| 51.4101 .0554| 2.1806 .0320 
STANDARD DEVIATION. 
apex, sin....| 188 0.7928+.0276| 0.4436+.0154| 2.1916+.0752) 0.4785+.0166) 0.3664 .0127) 2.5561=.0879| 1.8401+.0630) 0.0 
cestata, sin..| 106 1.0327 = .0478 4882+ .0226| 2.7498+.1273) .5116+.0237| .4025+.0187| 2.7761+.1285} 2.2000+.1019} .2938+.0134 
phea, sin....| 70 | 1.1638+.0663 4792+ .0280) 2.6092+.1477| .5465+.0311| .3850+.0219) 2.5561+.1456| 1.6638+.0948) .2039+.0117 
All, sin..... | 364 -9555 + .0239 4580+ .0114) 2.4738+.0618) .5083=.0127/ .3863+.0096| 2.6359+.0659) 1.9471 .0486| .1848+.0046 
apex, dex.. | 48 -9322 + .0641 .3968+ .0263) 2.2313+.1536) .3950+.0261| .2098+.0144) 1.9983 .1375| 1.7706+.1208) 1.0811+.0737 
cestata, dex.| 120 -8306+.0351 4053+ .0166) 2.3352+.1007) .4512+.0196) .3329+.0145) 2.3591+.1027) 1.9513+.0839) 1.0821+.0469 
pheea, dex...) 355 -8310+.0210) .4114+.0094) 2.2773+.0576) .4587+.0116| .3620+.0091) 2.7938+.0707| 1.8669+.0472| 1.0991+.0278 
All, dex....| 523 .8408+.0175 4085+ .0085) 2.2942+.0478) .4518+.0094) .3551+.0073) 2.6351+.0549| 1.8801+.0392) 1.0890+ .0226 
1The numbers are: Sinistral, 193, 109, 69; 371; dextral, 49, 121, 356; 526. 
The statistics relating to fecundity (table 178) combine the observations for 
the two years, because the material was collected during the same month of the 
year. A direct examination of the question proves that the relations are almost 
exactly the same in the two series. No real degree of differential fertility comes to 
light, although the dextral adults bear fewer young on the average and the several 
classes differ somewhat among themselves. 
In dealing with the facts of inheritance there is no difficulty where the direction 
of spirality is concerned, but in the case of the differential characters of the color- 
classes insuperable obstacles are encountered. The figures are given in full and 
in summary in table 179. It is remarkable that the total numbers of sinistral and 
dextral young agree almost exactly with the figures for the gravid adults. As the 
latter form about go per cent of the whole representative population, in both modes 
of coil, this agreement indicates a stable condition of the colony as regards the pro- 
portionate numbers of reversed and directly coiled snails. 
