90 VARIATION, DISTRIBUTION, AND EVOLUTION OF THE GENUS PARTULA. 
genetic factors for the positive production of the characteristic tooth in a greater 
number of cases. Hence there is only a false or coincident correlation between a 
color mode and the degree of tooth development. 
TABLE 41.—Partula gibba, Guam. Coast Central Region. 















Lip. 
Series. No. 
Yellow; Brown; 
White. yellow- brown- Pink. None. | Trace. | Small. 
brown. orange. 
Tumon: mitella, ca sae. 5 sate 2 1 
Oco: bicolorsj. scares dew eee 2 1 
mitellasge act ae ots | 7 
mitella-rubra............ 1 1 
vespera-rosea........... z 2 
vespera-cyanea.......... Z 2 
All. QY-ER. wee. see 14 13 
Timoneng: bicolor, se. v5, Sete ons eee 4 
mitellasid aoe eens 8 
mitella-rubra............ 4 
Pp eciet anta chica or me 16 
Dungcas: MIGEA ss cosa ween ae. 28 25 
mitella-rubra............ 1 
marginatass « veces leuk 6 
A ersaes eis sc ent eocas 35 25 
Agafia: rattella is cca tienes oem 29 3 
Aniguac: Dicolorss. fe aie ate Ze 
portellac on aod Pe e.s saan 194 47 
castanea-rubra.......... 2 2 
castanea-purpurea....... 1 1 
vespera-cyanea.......... 4 4 
PALL cure hee escane Calor eee 54 
Cemetery: gitella sqccntirc Saniewe 39 2 
Presidio, inner: mitella.........:.....+- 65 3 
Presidio, outer: mitella................. | 33 1 


EMBRYONIC MATERIAL. 
The statistics relating to the embryonic material are unqualified in their value 
for the determination of the reproductive rate of the species at the time that 
field-work was carried on. They are less useful for the problems of heredity, 
although as regards the question of mutual interbreeding on the part of the several 
color-classes they give positive results. 
No instance of fertility has been observed before the shell is completed by 
the formation of the flaring lip; it is only because the opposite is true in the case 
of P. fragilis that this statement is formally recorded. Like the egg-capsules of 
P. radiolata, those of gibba are clearly transparent and entirely devoid of calcareous 
impregnations in their walls. They are cask-shaped, ranging in length from 3.5 
to 4.5 mm., and in breadth from 3 to 3.5 mm. Still within the brood-pouch and 
