TERRESTRIAL MOLLUSCA INHABITING SOCIETY ISLANDS. 93 
They are distributed over a vast area extending from southeastern Polynesia to 
Mauritius and Bourbon. They are entirely absent from the Sandwich Islands, where 
the only operculated land shells are Helicine. Two species of Atropis only are recorded 
from the Marquesas Islands; but their existence in that group certainly wants confir- 
mation. Both Mr. Pease’s collector and myself searched in nearly all parts of the 
group without discovering a single example. In all probability the Society Islands 
are the eastern limits of this group of shells. At any rate I utterly failed to detect 
them at the Gambier and Paumotu Islands. 
In the Society Islands the typical form is represented by a group in which the keel 
gradually becomes evanescent, as in /Tuwaheinensis and scitula, or entirely absent, as in 
terebralis and producta. The three latter were classed by Mr. Pease in his genus 
Atropis. All the above species, together with Boraborensis and oblonga, usually 
have the body or penultimate whorl more or less angulated and frequently with a 
periphery keel. 
The animal of Huaheinensis varics from pale cinereous to tawny flesh-color with 
blackish tentacles, which latter are short, conical, blunt and transversely wrinkled. 
Eyes very conspicuous, black on enlargements at the hinder base of the tentacles. 
Head broad, emarginate in front. Muzzle slightly dilated and bilobed in front, and 
used in aiding locomotion. Foot small, oval, nearly half the length of the shell. 
O. Huanernensts, Pfeiffer. 
Hydrocena Huaheinensis, Pfeiffer, Proc. Zool. Soc., 1854, p. 308; Mon. Pneum., ii, p. 163. 
H. and A. Adams, Gen. Moll., ii, p. 300. 
Omphalotropis Huaheinensis, Pfeiffer, Mon. Pneum., iii, p. 177. Mart. and Langk., Don. 
Bism., p. 58, Pl. III, fig. 17. Pease, Jour. de Conch., 1869, p. 148, Pl. VII, fig. 9. 
Schmeltz, Cat. Mus. Godeff., v. p. 101. Pease, Proc. Zool. Soe., 1871, p. 476. 
Assiminea Huaheinensis, Marten, Ann. Mag. Nat. Hist., 1866, p. 206. 
Realia Huaheinensis, Pfeiffer, Mon. Pneum., iv, p. 221. Carpenter, Proce. Zool. Soe., 1871, 
p. 676. 
Hydrocena robusta, ‘* Pease,” MS. Carpenter, Proc. Zool. Soc., 1864, p. 676. 
Omphalotropis robusta, Crosse, Jour. de Conch., 1869, p. 148 (foot-note), Pl. VII, fig. 3. 
Schmeltz, Cat. Mus. Godeff., v, p. 208. 
Occurs in abundance, and widely diffused over Huaheine. It is also plentiful 
and of larger size in three or four valleys on the west side of Raiatea. At Moorea, 
where I obtained a few examples, it is of small size (5 mill.) and has the basal keel 
nearly or quite obsolete. On the ground in forests. 
Pfeiffer’s type specimens (9 mill.) were collected at Raiatea, and his var. 2 (6 mill.) 
at Huaheine. In one valley on the former island I discovered a large variety which 
attained a length of 11 mill. 
They vary considerably in color: pale luteous, corneous, brown, brownish red, 
reddish horn-color, rarely with a transverse brown or reddish band on the middle of 
the body-whorl, which latter is sometimes slightly angulated. The epidermis is very 
13 JOUR. A. N. 8S. PHILA., VOL. IX. 
