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 forbesi 



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, pi. 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. pi. 133, fig. 4y5), however, do not repre- 

 sent C. forbesi. 



Note. In the figures (pi. 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 apec- 

 imen photographed it is very thin and transparent. The photo- 

 graphs have also failed to show sufficiently well the dark color 

 of the lip. 



