PARTULA, TAHITI. 181 



Rurutu or Oheteroa (type loc.; Cuming). Cooks or Hervey 

 Is.: Mangaia (Garrett) ; Rarotonga (C. D. Voy). 



Partula hyalina BROD., P. Z. S. 1832, p. 32. REEVE, Conch. 

 Syst. ii, pi. 175, f. 1, 2; Conch. Icon. pi. 3, f. 14. PPR. 

 Monogr. iii, 451; Conehyl. Cab. p. 271, pi. 64, f. 19, 20. 

 GARRETT, Proc. A. N. S. Phila. 1879, p. 18 (Austral Is.) ; 

 Journ. A. N. S. Phila. ix, 1884, p. 65. MAYER, Mem. Mus. 

 Comp. Zool. xxvi, no. 2, p. 122, figs. 1, 2, la-lc (1902). 

 Bulinus hyalinus SOWB. Conch. Illustr. f . 9. Bulimus 

 hyalinus PFR. Monogr. ii, p. 67. 



Quite distinct 'by its milk-white color, and the very oblique 

 aperture, contracted in adult shells by a strong inner rib of 

 the lip. It might form a separate subgenus. 



The distribution of this snail on several widely separated 

 groups is remarkable. Such distribution is unparalleled by 

 any land snail of its size in Polynesia. I have not seen 

 specimens from Mangaia or Rurutu, but those collected by 

 Voy -at Rarotonga seem indistinguishable from Tahitian ex- 

 amples. It seems possible that it has been distributed by hu- 

 man agency, since it is not likely that a snail of this size could 

 be carried far over sea by hurricanes, 'as the minute forms 

 (Tornatellina, Pupidce etc.) no doubt have been. Still an- 

 other hypothesis : P. hyalina may be an ancient and 'conserva- 

 tive stock, which has survived from the time when these 

 mountain islands formed the sierras of a larger land mass. 



10. P. COMPRESSA 'Pfr.' Reeve. PI. 41, figs. 19, 20, 21. 



"Shell acuminately oblong, rather thick, obliquely pro- 

 duced towards the base, rather largely, compressed umbili- 

 cate. Whorls convex, obliquely striated, very slightly 

 spirally lineated ; last whorl rotundately angulated at the base. 

 Aperture oblong, lip reflected in a slanting direction, a little 

 contracted in the upper part. Dark chestnut brown, lip 

 and interior of the aperture livid purple." (Reeve). 



"Shell deeply rimate, ovate-conic, rather solid, under the 

 lens very minutely decussate; chestnut colored. Spire conic, 

 rather obtuse; suture marked with a white line. Whorls 5, 



