CHAPTER V. 
PARTULA RADIOLATA (PFEIFFER.) 
GENERAL CONSIDERATIONS. 
Partula radiolata (Pfeiffer) exists in considerable numbers in the island of 
Guam, where it is widely distributed as well; furthermore, it varies from place to 
place throughout the island, with the result that individual associations differ 
mutually as regards the average size and form of the shells, and also as regards the 
kinds and relative abundance of their component color-classes. For these reasons 
Partula radiolata is available for the detailed study of variation and geographical 
distribution and consequently it is far more valuable than salifana and fragilis, 
although the two forms described in the foregoing chapters are most interesting 
in other connections. The present species approaches but does not equal the 
remaining form, P. gibba, in its abundance and diversification throughout the island. 
The taxonomic history of radiolata is relatively clear. The original shells were 
named Bulimus (Partula) radiolatus by Pfeiffer in 1846,! and they were certainly 
obtained by Cuming, for the title of Pfeiffer’s communication explicitly credits them 
to that noted collector. Subsequently in 1849, Pfeiffer renamed the species cor- 
rectly as Partula radiolata. In the original account the habitat is given as New Ire- 
land, an island of the Bismarck Archipelago later called New Mecklenburgh; a 
similar error is perpetuated in Hartman’s list of 18812 with the citation of Cox as 
the authority; but Cox himself corrected the mistake and properly referred the 
species to Guam in a letter to Hartman quoted by Smith. 
In view of the abundance of radiolata at the present time and its unquestionable 
occurrence in some numbers about 1840, it is surprising that it was not recorded 
from the material collected by Gaudichaud-Beaupré which was described by 
Férussac, and which comprised gibba and fragilis as well, the latter being a species 
that is far less abundant than radiolata at the present time. On general grounds 
one would suppose that the pioneer naturalists did indeed secure specimens of 
radiolata which were lost, or were referred erroneously to other localities, or most 
probably were not properly distinguished from their associates living in Guam. 
The last possibility seems actually to be the truth. Quoy and Gaimard were 
members of the Freycinet expedition of 1819, and returned to Guam as members 
of the Astrolabe expedition in 1828. In their account of their zoological observa- 
tions! they deal at some length with Partula gibba under the name of Helix gibba, 
repeating Férussac’s original description and adding their comments on the animal 
and its habits. It seems certain that they had some specimens of radiolata in hand, 
for they write of a “Varietas, elongata, subflava, longitrorsum albo notata; peri- 
stomate ovali et albo”’; and later they wrote: “‘La variété que nous figurons, et 
qui est assez rare, se distingue par son plus grand allongement, par son overture 
assez réguliérement ovulaire, son péristome blanc, sa couleur jaune clair, marquée 
"1, Pfeiffer, Proc. Zool. Soc. London, part xIvip.31846. 
2 W. D. Hartman, Bul. Mus. Comp. Zool., vol. rx, No. 5, p. 186. 
3H. H. Smith, Annals Carnegie Museum, vol. 1, 1902, p. 439. 
4 Quoy and Gaimard, Voyage de l’Astrolabe, 1833, Tom. 2, pp. 113-115, plate 9, figs. 18-22. 
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