1884.] OF THE 'CHALLENGER' EXPEDITION. 271 



7, 8, 13, and 14 being from Ovalau ; 2, 4, 9, 10, 1 1, 12, and 15 from 

 Eandavu, and No. 16 from the Wai Levu, Viti Levu. 



Helix (Trochomorpha) latimarginata. (Plate XXIII. 

 figs. 14-14 b.) 



Shell depressed, acutely keeled, arched above, very slightly con- 

 vex beneath, deeply and rather narrowly umbilicated, uniformly dull 

 pale brownish. Whorls 5, slowly increasing ; the last convex above, 

 compressedly broadly marginate above the suture, sculptured with 

 oblique lines of growth, last near the aperture but very slightly broader 

 than the preceding, compressed both above and below the sharp 

 carina. Aperture small, with the basal margin receding and 

 thickened. 



Greatest diam. 15 millim., smallest 14; height 7. Umbilicus 

 about 2| wide. 



This species belongs to the same group as H. eurydice, Gould, 

 H. cressida, Gould, 77. swainsoni, Pfr., II . apia, Horn. & Jacq., and 

 some others, but does not seem to fall among the varieties of any. 

 The narrowness of the last whorl, the broad marginatum above the 

 suture (the margination being a little darker than the rest of the 

 surface), the dull uniformly pale brownish colour, the thickened 

 lower margin of the aperture, and the flattish lower surface are the 

 principal distinguishing features of this species. 



Friendly Islands. 



Eight species collected at Tongatabu have all been previously 

 recorded from these islands, and, with the exception of Nanina 

 tongana, are not restricted in their distribution to this group, the 

 majority having been met with at the Samoa Islands somewhat 

 further north. The species are — 1. Nanina perpolita, Mousson ; 

 2. N. tongana, Quoy & Gaimard ; 3. Helix (Patula) gradata, 

 Gould; 4. Helicina fulgora, Gould; 5. II. musiva, Gould; 6. Om- 

 phalotropia variabilis, Pease ; 7. l J hysa sinuata, Gould ; 8. Melania 

 inhonesta, V. d. Busch. 



Society Islands. 



The following eight species were collected at Lake Waihiria on 

 the island of Tahiti. 



1 . Nanina tongana, Quoy & Gaimard. 



A single specimen only was obtained, agreeing in every respect 

 with others collected at Tongatabu. This appears to be the same 

 species as Helix conula of Pease, also founded on Tahitian shells. 



2 & 3. Parttjla, sp. 



Seven specimens of this genus in worn condition apparently belong 

 to two distinct species which I have been unable to identify, and 

 which it would be unwise to describe as new without paying special 

 attention to the whole of the genus. 



19* 



