28 TERRESTRIAL MOLLUSCA INHABITING SOCIETY ISLANDS. 
and fasciation; they vary some in the elevation of the spire. The various species of 
this genus are so closely allied that it is difficult to express in words the specific 
differences. 
Compared with pallens it is smaller, color different, the band always narrow, and 
the umbilical region more excavated. The whorls are also a little more flattened. 
The obliquely arched columella will at once separate it from trochiformis. 
Genus PATULA, Held. 
P. MOpICELLA, Ferussac. 
Helix modicella, Fer., Mus. Deshayes, in Ferussac’s Hist. Moll., i, p. 90, Pl. LXAXXVI, 
fig. 3. Pfeiffer, Mon. Hel., iii, p. 92; vii, p. 149. (Patula) Paetel, Cat. Conch., p. 92. 
Nanina modicella, Gray, Cat. Pulm., p. 129. 
Pitys modicella, Pease, Proc. Zool. Soe., 1871, p. 474. 
Patula modicella, Schmeltz, Cat. Mus. Godeff., v, p. 98. Mousson, Jour. de Conch., 1873. 
p- 104. 
Pithys Atiensis, Pease, Jour. de Conch., 1870, p. 394. 
Pitys Atiensis, Pease, Proc. Zool. Soc., 1871, pp. 453, 474. 
Patula Atiensis, Garrett, Jour. Acad. Nat. Sci. Phila., 1881, p. 386. 
Helix Atiensis, Pfeiffer, Mon. Hel., vii, p. 165. 
Patula vicaria, Mousson, Jour. de Conch., 1871, p. 11, Pl. III, fig. 2; 1878, p.104. Schmeltz, 
Cat. Mus. Godeff., v, p. 93. 
Helix vicaria, Pfeiffer, Mon. Hel., vii, p. 187. (Patula) Paetel, Cat. Conch., p. 93. 
This species, which is distributed throughout the group, is found adhering to the 
under side of dead wood in the lowland forests. It appears to be more rare in the 
Paumotus, and is widely diffused over the Harvey Islands. I also obtained it in the 
Tonga, and Dr. Graffe gathered examples in the low coral islands of the Ellice group, 
which gives it a wider range than any other Polynesian species. 
Dr. Pfeiffer, who was unacquainted with this species, copies Deshayes’ description, 
and, on the authority of Mr. Cuming, cites Tahiti as its habitat. He describes it as 
follows :— 
“T. minima, orbiculato-depressa, tenuissima striata, late umbilicata, corneo-fulva ; 
anfr. 44 convexusculi, sutura canaliculata separati; apertura simplex, rotundato- 
semilunaris. Diam. 3, alt. 1} mill.” (Pfeiffer). 
The above brief diagnosis accords closely with the numerous examples before me. 
Though occasionally uniform fulvous horn-color, and sometimes pale corneous, they 
are nevertheless frequently ornamented with faint reddish brown stripes and tessella- 
tions. The four and a half whorls are separated by a channeled sutural line. The 
spire is slightly convex or planulate. Whorls convex, last one moderately flattened 
above the periphery, and the strive consist of fine, very crowded, sharp, lamelliform 
riblets, which are very slightly biarcuate. The perspective umbilicus is nearly a third 
of the major diameter of the shell. 
