PAKTULA. 125 



that in both cases the sinistral snails breed truer to their type than do 

 the dextral. 



Partula otaueitana var. lignaria Garrett. 



Figs. G, 7. 



The snail represented in Fig. 6 is found in Tip^rui valley. The 

 ground-color of the shell is quite similar to that of snails of color-type 5, 

 but they are distinguished from the latter by the presence of a more or less 

 distinct whorl-stripe, which extends from the suture of the spire through 

 the middle of the body-whorl. In a few individuals there are two separate 

 whorl-stripes, one through the middle of the body-whorl and the other 

 adjacent to the suture. These snails constitute 2G.5 per cent of the fauna 

 of Tipajrui valley. All of the specimens obtained were dextral, as were also 

 the young dissected from them. Nineteen adults yielded thirty-three 

 young, of which number twenty-eight were similar in ground-color to the 

 type of snail shown in Fig. 5, while two were as light as the snails 

 represented in Figs. 3 and 8, and three were slightly darker in color 

 than the parent shells. 



Of these young ones 41 per cent exhibit a distinct whorl-stripe, while 

 59 per cent are unstriped, and resemble in all respects the normal young of 

 snails of type 5. Indeed among the sixty-one young taken from adults 

 of type 5 in Tiprerui valley, five exhibit the whorl-stripe characteristic of 

 the young of type 6. There can be but little doubt, therefore, that in 

 type 6 we have a race of snails which is derived from type 5, and which 

 imder conditions of more perfect isolation might in time develop into a 

 distinct form. It is possible that this tendency may be prevented in 

 Tiptcrui valley by constant intercrossing between the adults of types 5 

 and 6. 



Fig. 7. 



The sinistral snail with two whorl-stripes, which is represented in Fig. 7, 

 is found in Hamuta and Pirse valleys, where they constitute 3 per cent 

 and 4 per cent respectively of the snail-fauna. In Hamuta valley four 

 adults yielded seven young, five of which were as light in ground-color 



