EXPLANATION OF THE PLATE. 



Five species of snails are represented on the Plate ; as follows : Figs. 1, 2. Fartula 

 hyalina Broderip ; Figs. 3-8. Fartula otaheitana Bruguiere ; Figs. 9, 10. Pavtula filosa 

 Pfeiffer ; Figs. 11-13. Partula sinistrorsa Pease ; Figs. 14, 15. Pariula nodosa var. 

 sinistralis Pfeiffer = P. triUneata Pease. 



Figs. 1-15 represent adult or nearly full-grown snails, while Figs. l''-3'', etc., show 

 young snails taken from adults of corresponding number. Thus : 3" is a young one taken 

 from the type of snail represented in Fig. 3, etc. These Figures of young snails are four 

 times the natural size, while the Figures of adults are one and a half times the natural 

 size. • 



Figs. 1, 2. Partula hyalina. 



Figs. 3-8. Partula otaheitana. 



Figs. 9, 10. Partula filosa. 

 Figs. 11-13. Partula sinistrorsa. 



From a snail obtained in Tipterui valley 

 near Papeete. This species is found in 

 all of the valleys of Tahiti, but is never 

 abundant anywhere. 



These Figures show various common color- 

 varieties of one and the same species of 

 snail. Figs. 3-6 are taken from snails of 

 Tipoerui valley ; Fig. 7, from Pirffi ; and 

 Fig. 8, from Hamuta valley. 



Fig. 6 represents a color-variety derived 

 from the form shown in Fig. 5 ; while 

 Fig. 8 is similarly derived from Fig. 3. 

 All of these snails are dextral in TipsBrui, 

 and sinistral in Pirse valley ; while in the 

 two intermediate valleys of Fautaua and 

 Hamuta some individuals are dextral and 

 others are sinistral. In Hamuta valley 

 the apex of the shell is often tinged with 

 red-brown, or pink, as in Fig. 8. This is 

 due to the wearing away of the outer epi- 

 dermis of the shell. 



A species obtained in Pirre valley. 



Color-varieties of a species of snail obtained 



in Vaihiria valley. 



Figs. 14, 15. Partula nodosa var. sinistralis. Color-varieties of a form obtained only in 



Maruapoo valley. 



