42 TERRESTRIAL MOLLUSCA INHABITING SOCIETY ISLANDS. 
E. TANE#, Garrett. 
Pitys Tanex, Garr., Proc. Cal. Acad. Sciences, 1872, iv, p. 204. Proc. Acad. Nat. Sci. Phil., 
1873, p. 234, Pl. IIT, fig. 65. 
Patula Janex, Schmeltz, Cat. Mus. Godeff., v, p. 938. (Typ. err.) 
Helix Janex, Pfeiffer, Mon. Hel., vii, p. 481. (Name only ex. Schmeltz.) 
Helix Tanex, Pfeiffer, 1. c., p. 482. (Name only.) 
Helix Boraborensis, Pease, MS., Mus. Pease, 1863. 
Very abundant and restricted to Borabora and Maupiti, where they live on the 
ground in forests. 
When I wrote my description of this species I had only half a dozen specimens of 
Boraborensis named from Pease’s types. Having subsequently gathered several 
hundred of the latter species at Borabora, I find the two species gradually intergrade. 
Maupiti specimens are remarkably uniform in shape, sculpture and coloration. The 
Borabora shells, on the contrary, are subject to considerable variation in all the above 
characters. In order to incorporate the characters of the latter, I redescribe it as 
follows :— 
Shell widely umbilicated ; depressed, lenticular, rather thin, corneous or brownish 
horn-color, irregularly spotted and rayed with rufus-brown, rarely unicolored ; sculpture 
consisting of very small, rude, crowded, oblique, subarcuate, raised striw, with remote 
larger ones intermixed; the latter sometimes absent in the Borabora shells, and in the 
immature they are frequently membraneous and lacerated ; spire more or less convex, 
sometimes nearly planulate, rarely depressly conoid; apex mucronated, generally. 
suture lightly impressed, occasionally margined by the continuation of the periphery- 
keel. Whorls 55-74, convex or subplanulate, very narrow, slowly and regularly 
increasing, last one not deflected in front, rarely sulcate above, periphery acutely 
carinate; base more or less distinctly angulate, rarely rounded; umbilicus funnel- 
shaped, a little more than a third the greater diameter of the shell. Aperture oblique, 
irregularly rhomboid-luniform ; parietal region with two lamin, the lower one short 
and rarely visible without breaking away a portion of the peristome ; palate with two 
to four deeply seated lamelliform teeth, the one above the keel sometimes absent ; 
peristome thin, simple, straight ; columella not expanded. 
Major diam. 45, height 15 mill. 
The above measurement is the average size of Maupiti specimens. The Borabora 
shells are sometimes a trifle larger, and some have the spire more elevated. The 
young are occasionally dark brownish, with rounded whorls, which are conspicuously 
undulated, and the strive very uniform. Individuals are not infrequent which have the 
whorls more tightly coiled, the striation finer and very uniform in size. In the latter, 
the body-whorl is deeper and the keel more obtuse. 
The umbilical membrane or diaphragm, alluded to in my remarks on cretaced, is 
frequent in the Borabora shells, but not observed in those from Maupiti. 
