PARTULA OTAHEITANA. 251 
The dominant color-form of sinistralis is cestata, with some modifications of the 
bands. Among the unbanded snails one finds apex represented in certain valleys, 
but in very few. The class that is equivalent to the sznistrorsa phea is sometimes 
a single highly varying group; more often, however, it is split up into somewhat 
sharply demarcated color divisions, one of which is the confluens described earlier, 
while the shells of the other are distinctly strigated, like some of the s7nistrorsa 
specimens found in Tenaire Valley; as before, the latter color-type will be called 
striata for brevity and convenience. The absolute and relative numbers of the 
snails referred to these color-classes are given in table 196, which supplements the 
more general numerical tabulations given in table 56. 
TaBLe 196.—Partula otaheitana sinistralis. Census of the color-forms. 
Number in adult population. Per cent of adult population. 
A OSS 
Valley. No. of Sinistral. Dextral. Sinistral. Dextral. 
2 ees | 
apex. | cestata. | phea. | apex. | cestata.| phea.| apex. | cestata. | phea apex. | cestata. | phea. 
sheobieeee 459 35 333 91 7.6 72.5 1.9 
Papeiti.... 475 8 209 258 56 Biota lod 44.0 54.3 26.00 
Temarua.. 563 1 365 195 fs 2 aD 0.2 64.8 34.6 0.4 
Vaipoo.... 62 “se 49 13 Ac Soe Sys ba 79.0 21.0 58 
Tearatapu. 30 AS 15 15 ws 5.010 ai aK SOO |) SO. 
Opiriroa... 152 see 112 40 ae ic an Pat Wall 26.3 
Otuna..... 347 Bo 237 110 at shy a eeaits 68.3 Sil oo Aste dikes 
Maruia.... 129 4.0 61 43 59 17 8 ele 47.3 53}.583 SZ 6.2 
Tereehia.. . 130 oo 58 12 ute 60 Fre ace 44.6 9.2 510% 46.1 ore 
Tiamao... 326 a 169 8 1 138 10 Sars 51.8 2.4 0.3 42.3 Se 
Vaipuarii. . 180 Be 142 38 aoe Sin ays wae 78.9 Diol wks 5.0% nora 
motalevarcrer 2,853 44 1,750 823 1 217 18 1S) 61.3 28.8 0.03 7.6 0.6 
1One dextral embryonic snail. 
DESCRIPTION OF THE COLONIES—TEOHU TO VAIPUARII VALLEYS. 
TrEouu VALLEY. 
Most of the specimens from this valley were taken in 1906, during the warmer 
season; a small series was also secured in 1907. The valley is a small one, as the 
charts and diagrams have shown, and the occurrence of some forest growth between 
its mouth and those of the adjacent valleys renders it almost continuous with its 
neighbors. Nevertheless, the Teohu colony of sinzstralis is most unique. Shells of 
the apex coloration (plate 31, figs. 57 to 59) amount to 35, some of them displaying 
the effects of decortication so as to be nearly white, save for the tinted spire (fig. 57). 
Banded shells number 333, constituting a class that will be called cestata, like its 
counterpart in sinistrorsa, although the details of the banding are somewhat differ- 
ent (plate 32, figs. 1 to 8). What may be regarded as the central type of this class 
is a shell with three clearly marked dark stripes on a lighter yellowish-brown back- 
ground (plate 32, figs. 1 and 2); even in this the middle band is relatively narrower 
than in the typical cestata of sinistrorsa. The variates grade to darker forms in many 
cases, where the background becomes somewhat “‘filled up”’ by cross-strigations, but 
the bands never suffuse as they do in some of the subordinate color-forms to be 
described later. By the lightening of the middle band, save along its lower or 
“right” border (plate 32, figs. 3 and 5), a type is produced which leads to a still more 
modified pattern, in which the sutural and basal stripes have vanished on the body- 
