262 CERION, GROUP XI. 



hermit crabs wore found along Fresli Creek near the settlement. 

 One of these mutilated specimens is figured. 



Form bimarginatum Mayn. (pi. 43, figs. 60, 61, 62) is white, bluish 

 or gray-white, with brown aperture. Ribs 23-26 on penult, whorl. 

 The parietal ridge is usually well elevated, and the outer lip is 

 doubled, a thin lamina rising a short distance behind the edge (fig. 

 60j. This is quite unlike the heavy flange of C. glans griseum^ when 

 typically developed, but varies a great deal, and in some specimens 

 the lip is identical in structure with small specimens of griseum. The 

 parietal tooth is strongly developed and often indistinctly doubled by 

 a callous buttress or accessory tooth on the left side of the principal 

 one. The young have five teeth, unlike New Providence forms, in 

 which only the columellar lamella is developed in young shells. This 

 form is found on Green Key, off Andros (figs. 60, 62), and Little 

 Galden Key, Middle Bight, Andros (fig. 61). Several forms are 

 distinguished by Maynard. No. 1 (pi. 43, fig. 61) occurs in the 

 thicket away from the beach, on both keys, is larger with " an incli- 

 nation to assume a beveled margin and single tooth, with a darker 

 interior;" ribs 20-27 on penult, whorl. Form No. 2 (fig. 62) is quite 

 small, bluish, sometimes mottled, the parietal tooth is simple and the 

 lip merely expanded and a little thickened, like the small form of 

 griseum. It occurs among grass on the rocks at Green Key. 



Nine specimens obtained on trees and bushes on Green Key are 

 thinner than bimarginatum, externally and internally of a " beautiful 

 waxy white," the peristome thin, simply expanded a little, not 

 double. Mr. Maynard has given these individuals the name S. 

 bimarginata cera (pi. 43, fig. 63). 



The form called S. pilsbryi by Maynard (pi. 43, fig. 64), occurs on 

 an islet called Goat Key, about one-eighth of a mile long and no- 

 where over fifty yards wide, situated about a half mile directly west 

 of Little Galden Key, Middle Bight, Andros. The shell is blue- 

 white, often having a dark basal streak, and more or less indistinct 

 dark marking on the cone. The lip is white, narrowly reflexed and 

 more or less thickened. The interior is white, suddenly becoming 

 dark in the throat. Parietal lamella stout. Length 21-27 mill. 

 The typical form occurs on the eastern half of the key. On the 

 western half the shells are yellowish or ivory-white, copiously mottled 

 with dull brown and purple brown, somewhat larger, the interior 

 dark brownish throughout. The parietal lamella approaches the 



