30 THE NAUTILUS. 
avus, as described by Pfeiffer (Proc. Zool. Soc. Lond., 1852, 
p. 83) are constant and may be tabulated as follows; 
Camaena avus Camaena forbest 
whorls 4 whorls 5 
last whorl carinated last whorl rounded 
aperture scarcely oblique aperture oblique as usual in 
Camaena 
peristome thick | peristome slightly thickened 
peristome white peristome dark 
margins joined by thick callus margins joined by very thin 
transparent callus 
altitude 18 mm. altitude 29.5 mm. 
The figures of Camaena avus in the Manual of Conchology 
(ser. 2, vol. 6, 1890, pl. 27, f. 15, 16, 17) were copied from 
Pfeiffer’s original figures in the Conchylien Cabinet, t. 157, 
f. 12-14, and, besides showing a much more widely expanded 
and thickened peristome than occurs in C. forbesi, also show that 
C. avus is far more widely umbilicate. 
Hidalgo (Obras Malacologicas, Estudios preliminares sobre 
la fauna malacologica de las Islas Filipinas, 1901, p. 196) states 
that the C. avus in the Quadras collection is similar to the C. 
avus of Mollendorff (Verz. Philipp. Landmollusk., 1898, p. 64) 
but differs from C. avus of Pfeiffer in size, in the bands, and in 
the umbilicus. It is possible that the C. avus of Quadras and 
Mollendorff is equal to C. forbesi. The figures of C. avus given 
by Hidalgo (loc. cit. pl. 138, fig. 4y5), however, do not repre- 
sent C. forbest. 
Note.—In the figures (pl. I) reproduced from photographs 
by Mr. George Nelson, the reflected light on the glazed surface 
of the parietal wall greatly exaggerates the parietal callus, mak- 
ing it appear somewhat heavy and opaque, whereas in the spec- 
imen photographed it is very thin and transparent. The photo- 
graphs have also failed to show sufficiently well the dark color 
of the lip. 
