PARTULA RADIOLATA. 45 
Closely related to the foregoing is the form here called pallida on account of 
the general dilution of the typical colors (figs. 20 to 26, plate11). The ground-color is 
very pale with only a slight tinge of yellow, and the brown streaks are fewer; the 
inner wall of the last whorl is also much paler in color. It is possible that certain 
shells referred to this class are really pale flavea, but if that is the case, they are 
nevertheless distinguishable in the phenotypic sense. The lighter tints are not the 
result of senescent changes, for partly-grown individuals are quite as easily separated 
from their flavea associates (compare figs. 26 and 32, plate 11). There are many 
instances where the attenuation of the colors leads to a virtual albinism, manifested 
by the inner and outer surfaces, including the whole apical region (fig. 21, plate 11). 
This color class is next to flavea in abundance throughout the island. 
The third form like the second is close to the fundamental flavea group with 
which it appears to intergrade so as to make it difficult in some instances to effect a 
satisfactory separation of the two classes; no such difficulties are encountered in . 
other colonies. —The name employed is fulva, in recognition of the fox-red tinge of the 
ground-color, which confers a somewhat fleshy cast to the whole shell; darker streaks 
of the same color traverse the whorls transversely (figs. 33 to 36, plate 11). In clear 
contrast with flavea, the apex, the general outer surface, and the inner walls 
display the reddish coloration. Such are the fulva shells found in the East Central 
Region; those of the South Central Region are not so reddish, but are properly to 
be assigned to the fulva class, even though their colors are sometimes rather pale. 
Presumably fulva is the variety mentioned by Pfeiffer as “testa carnea, radiis cinna- 
momeis,” but the question of correspondence is not essential. 
Just as the three classes described above constitute a natural subdivision, so 
the three remaining types are more intimately related mutually. The most 
abundant of these is strigata (figs. 37 to 44, plate 11), in which the shell is clearly marked 
with brown or purplish-brown streaks alternating with lighter areas. The yellowish 
and light-reddish shades of flavea and fulva are never displayed. The apex is nearly 
or quite uniform in color and agrees with the darker strigations of the larger whorls, 
while the inner surface is colored like the outer. Partly-grown individuals of this 
class are distinctly marked, even when they are very small (figs. 43, 44, plate 11). 
This is certainly the form named P. radiolata rushit by Pilsbry in the Manual (loc. 
cit., p. 318). The description applies, and the locality given by Rush as “ Port San 
Luis d’ Apra”’ is the harbor on which are situated the Cabras and Orote areas, where 
the present material was procured. In my own opinion the form does not merit full 
varietal standing, but should take its place as a color-type among the others of its 
species. The occurrence of this form in the Lower Ylig locality is noteworthy, as 
that area is far removed from the Apra Region, in which strigata has its present 
headquarters; yet the Ylig specimens are unmistakable members of this color-class. 
One of the most interesting types is the next, denoted strigata-helix (figs. 
45 to 48, plate 11). The shells resemble those of strigata in general appearance, but 
the lines are finer and closer as a rule. The distinctive feature is the revolving 
purple or purple-brown helix along the borders of the uppermost whorls; this 1s 
displayed by many of their embryonic young from the very outset of shell formation, and 
