Occasional Papers of the Museum of Zoology 73 



and stained with brownish. The whorls of this lot and the preceding one 

 are somewhat higher and more swollen than in the other shells. 



Bel. Quite common (34 specimens collected). Thin, white and trans- 

 parent; thickly covered with gelatinous material and usually with one 

 to three egg-masses stuck to the shell. Mostly with one to four rather 

 heavy white varices, which must correspond to resting periods in the 

 growth of the shell; at these places, the plane in which the whorls are 

 coiled is apt to change slightly but sharply, so that an irregular shape 

 results. In the umbilical region of some specimens, the last whorl com- 

 pletely covers a portion of the penultimate whorl. 



Description of Curacao specimens. Shell : dextral in form. 

 Color: clear white and transparent, or opaque and stained 

 with brownish; when alive it appears reddish with coppery 

 shadows, as the color of the animal shows through. Whorls: 

 4 to 5 ; quite rapidly increasing in diameter ; sutures shallow 

 on umbilical side but deeper above. Last whorl : somewhat 

 flattened above, less so below ; rounded to scarcely subcarinate ; 

 growth sculpture regular and well marked ; impressed, spiral 

 lines irregular and sometimes almost obsolete; not hispid. 

 Earlier whorls : rounded above and below, but the succeeding 

 whorls obscure the convexity in the umbilicus. Apical whorls : 

 easily seen in umbilicus, but deeply sunken and scarcely visible 

 from apical side. Umbilicus : shallowly and regularly concave ; 

 less than 1/3 the major diameter of the shell. Aperture : 

 oblique, very variable in shape ; elliptical to semilunate ; usu- 

 ally twisted downwards, sometimes markedly so, but may even 

 project slightly upwards. Peristome : simple, sharp ; parietal 

 callus thin. 



P. palUdus has a characteristic tendency for each whorl to 

 twist slightly downward from the plane of the preceding one ; 

 the amount of this is often irregular so that the umbilicus may 

 be markedly elliptical and the exposed portions of the earlier 

 whorls very variable in width. Adams described this species 

 as scarcely 3-whorled, but he must have counted the whorls 

 as visible from the apical side, as smaller specimens in the 

 A. N. S. P. (no. 62014, from Kingston, Jamaica, and other 

 lots) show 4 whorls, are dull horn-colored, and more closely 



