1888.] NATURAL SCIEXCES OF PHILADELPHIA. 289 



The relationship of the species of Poecilozonites to one another is 

 shown by the similarity of the radulse and jaws, and of the external 

 characters of the animal ; and in the shells, which at first glance 

 seem to be a heterogeneous assemblage, by the callus which coats 

 the columella, the compression of the whorl below the periphery, and 

 especially by the color-pattern, Avhich is the same in all the species, 

 consisting of zigzag flammules radiating from the sutures. In P. 

 bermudensis the flammules coalesce into continuous bands above and 

 below the periphery in the adult ; but an examination of young 

 specimens reveals the same pattern that is found in P. circumfirmata, 

 P. reiiiinna, etc. The internal spiral lamella of P. circumfirmata 

 would incline one at first to separate it from the 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 reinianiis. 



b. Aperture angulate below ; umbilicus narrow 



bermudensis, nelsoni. 



Poecilozonites bermudensis PtV. (pi. xvii, figs. e. c.) 



The typical species is a form of about twenty-five mill, diameter, 

 solid, coarsely irregularly striate and acutely carinate at the per- 

 iphery ; 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. xvii, fig. e). The base is con- 

 vex, and not indented around the narrow and deep umbilicus, 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. circumfirmata. 



The radula (pi. xvii, fig. c) is rather long. The central teeth have 

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

 below their lower margins, with well-developed cutting points, the 

 side cusps short, attaining about the middle of the basal plate, and 



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