Land Snails of Ulithi Atoll — Harry 
215 
these islands. It is equally probable that it in- 
dicates ecological diversity. 
Tourist snails often have no close relative 
native to the area in which they are introduced. 
This rule may have frequent exceptions (Harry, 
1964). Among the present fauna of Ulithi 
there is no single species which is certainly a 
native, i.e., which has evolved on that island. 
Thus we can not apply this criterion here. There 
are nearly as many genera and families as there 
are species on Ulithi. The chief exception is the 
Omphalotropidae, which contains two or three 
species of one genus. 
Introduced snails often occur in greater abun- 
dance in their new home than in the area where 
they evolved as indigenous snails. Most of the 
snails reported herein were abundant. But until 
we know the natural areas in which the species 
of the present fauna evolved, such comparisons 
can not be made for them. 
SYSTEMATIC ACCOUNT 
Because the pulmonates have been relatively 
well studied, only the more recent monographic 
literature is cited for each species. Recent works 
with extensive descriptions and figures are avail- 
able for a few of the prosobranchs also, but for 
several it was necessary to describe and figure 
them anew, since they have received no adequate 
treatment in the literature. All the records of 
species from Fais cited below are given on the 
authority of Dr. C. M. Cooke. 
Order pulmonata 
Family ELLOBIIDAE 
Pythia scarabaeus (Linne) 
Notes on the growth changes in the shell, 
and other data on this very common species 
were presented in an earlier paper ( Harry, 
1951). The confused nomenclature in this 
genus allows only ex cathedra identification of 
species at present. The possibility that some 
species might be tourist snails should be kept 
in mind in further systematic studies of the 
group. 
Family VAGINULIDAE 
Several specimens of (apparently) a single 
species were collected, but were lost through 
unsuccessful attempts to maintain them alive. 
Lacking data on the internal anatomy, we 
can not provide even a generic identification. 
Members of this group have been incriminated 
as tourist snails (H. B. Baker, 1925; Solem, 
1959). 
Family TORNATELLINIDAE 
Lamellidea subcylindrica? Mollendorff 
All of the few specimens were given to Dr. 
Cooke, who noted that his identification was 
tentative. The species was described and illus- 
trated by Pilsbry and Cooke (1915), and men- 
tioned in Cook and Kondo (1960:183). The 
latter note that it occurs on several islands of 
the Marianas. 
Family PUPILLIDAE 
Nesopupa ponapica Mollendorff 
Pilsbry (1920) reported this only from "Car- 
oline Islands, Mpomp, Ponape,” but Mollen- 
dorff (1900) thought it might be only a 
subspecies of N. tantilla (Gould), which is 
widely distributed in Polynesia. 
Gastrocopta pediculus Shuttleworth 
Pilsbry (1918) reported that this species has 
been found on nearly every inhabited atoll and 
high island of Polynesia, Micronesia, and Mela- 
nesia where small land shells have been sought. 
He also reported it in Hawaii, the Philippines, 
and New South Wales, Australia. 
Family subulinidae 
Opeas oparanum Pfeiffer 
Pilsbry (1907) could recognize only this 
species and Lamellaxis gracilis Hutton from all 
of Polynesia, where they are known to be widely 
distributed by commerce. Several other species 
of this family are known to be widely distrib- 
uted in the Pacific islands today. 
Family ZONITIDAE 
Discoconulus sp. (juvenile) 
H. B. Baker (1941) recorded only a single 
species in this genus, in his monograph of the 
Zonitidae of the Pacific. While all his records 
