196 THE BERMUDA ISLANDS. 



• 



which is the same in all the species, consisting of zigzag flam- 

 mules radiating from the sutures. In P. Bermudmsis the 

 flammules coalesce into continuous bands above and below 

 the periphery in the adult; but an examination of j'oung 

 specimens reveals the same pattern that is found in P. circum- 

 firmata, P. Reiniana, etc. The internal spiral lamella of P. cir- 

 cumfirmata would incline one at first to separate it from tbe 

 other species; but it is scarcely of generic importance, in 

 view of the fact that in all other characters the species is very 

 similar to P. Bermudensis, etc. 



The following analysis shows the inter-relations of the 

 various species : 



A. Base of shell with a revolving lamina within. 



circumfirmatus^ discrepans. 



B. Base of shell without lamina. 



a. Aperture rounded below ; umbilicus wide Reinianus. 



b. Aperture angulate below ; umbilicus narrow 



Bermudensis, Nelsoni. 



FtBcilozonites BermudenBis, Ffr. (PI. 16, figs. e. c.) 



The typical species is a form of about twenty-five mm. 

 diameter, solid, coarsely irregularly striate and acutely car- 

 inate at the periphery ; a broad chestnut band usually encircles 

 the shell above the periphery, and another below it, but these 

 are sometimes absent; the inner whorls of the spire usually 

 retain traces of the original color-pattern of radiating flames, 

 and the base in young examples is radiately streaked (PI. 16, 

 fig. e). The base is convex, and not indented around the nar- 

 row and deep umbihcus, but is angulated at its margin ; the 

 parietal wall is generally covered by a shining white layer, 

 with which the interior of the shell is lined. Reeve, Tryon 

 and other authors have figured the shell of this species. 



The jaw is like that of P. circiimfirmatus. 



The radula (PI. 16, fig. c) is ratber long. The central teeth 

 have basal plates almost as broad as long, the median cusps 

 projecting below their lower margins, with well-developed 



