122 EXPEDITION OF THE "ALBATROSS," 1899-1000. 



are usually dextral or siuistral respectively, but this is not invariably the 

 case. It is interesting- to observe, however, that idl of the }'Oung developod 

 within any given adult are either dextral or sinistral, never some of them 

 dextral and others sinistral. The young are born one at a time ; three 

 eggs and two or three young snails in various stages of development being 

 often found in a single adult animal. At the time of birth the shell of the 

 young one comprises two and a half whorls. No young are developed 

 until after the lip of the adult shell has been completely formed, 



Partula hyalina Broderip. 



Flijs. 1, 2; T'-r. 



This snail is found in all six valleys, but is never abundant ; constituting 

 but 2| per cent of the total number of snails in Piras, 3 per cent in Hainuta, 

 12 per cent in Fautaua, 7 per cent in Tipairui, 1 per cent in Maruapoo, and 

 2 per cent in Yaihiria valley. It is readily distinguished from all the otiier 

 snails by its milky-white, translucent shell, and the absence of a tooth upon 

 the columella. Every individual found is dextral, as are also the young 

 taken from the adults. In all forty-four specimens were obtained, and 

 nineteen of these yielded fifty-five young snails. The young are all white 

 in color, and show no tendency to intergrade with the young of anj' other 

 species, hence we conclude that this is a true species separate and distinct 

 from any other snail of the six A-alleys. 



Partula otaiieitana Bruguiere. 

 Fi(js. 3-8. 



Pircc, ITamida, Fautaua, and Tipcerid Valleys. The relationships of the color- 

 types represented in Figs. 3, Jj-i ^^ ^'"^ 8. 



These forms, which are represented in Figs. 3, 4, 5, and 8, arc mere 

 color varieties of one and the same sjjecies. They are found in Pira), 

 Ilanuita, Fautaua, and Tipa^rui valleys, but appear not to exist: in I\Iarua- 

 poo or Vailiiria. Fig. 3 represents the lightest colored type, where the 

 entire shell is of a horny-yellow hue, while Fig. 4 represents the darkest 

 type, the shell being of a uniform rich brown. In Fig. 5 we see a horny- 



