240 



ON THE TOPOGKAPIIY AND CIEOLOOIT 



extending even over the base of the body whorh Aperture elongated and rounded in advance. Length about .15 

 inch. 



A very solid species recoguizablc by its uniform, large ribs and produced aperture. 



LACUNA. Turt. 



L. x^unctata. Gabb, n. s. 



Shell small, spire elevated, variable in height, as long, or longer than the mouth ; whorls six, convex, widening 

 towards the base ; base rounded, umbilical groove bordered by a sharp margin ; aperture nearly round. Surface 

 smooth, covered by minute colored spots, arranged in pretty regular quincunx. 



The original color seems to have been more or less a light brown or reddish, with 

 dark spots ; but usually in the fossil the dark spots are preserved as an opaque white 

 or a semi-ti'anslucent ground. 



This shell is living in the West Indies, but I cannot lind it described. 



TURRITELLA. Lam. ' ' 



T. tornata. Guppy, Quart. ,Jour., Vol. XXIL, p. 580, pi. 2(;, fig. 13. •' ' 



A vciy slender species, recognizable by its beaded ribs. Mr. Guppy's description 

 applies very well to a single variet}^ Besides it, there is one form, with the same 

 large ribs, but beaded all over ; another with the upper rib double ; and still a third 

 with the lower rib much the more prominent of the two. In addition to these, there 

 are several less marked variations. 



T. planigyrata. Gappy, Proc. Sci. Soc. Trinidad, 18G7, p. 169. 



Shell elongate, many whorled ; whorls convex, the nearer ones flattened in the middle, marked with three or four 

 larger, and a great many smaller ribs covering all of the sides and base. Ajjerture sub-quadrate, inner lip encrusted 

 and reflexed. 



With a much wider apical angle than T. tornata^ and convex sides. This species 

 differs from both of the preceding by the nearly unifoi-ni size of the libs which are 

 all nearly thread-like and cover alike the sides and base of the shell. It is not unlike 

 T. ungulina in its surface, but differs in having" a quadrate mouth, instead of its being 

 elongate. 



T. exoleta. Linn., sp. 



I have the specimens of this species, showing- quite distinctly the squamose lines 

 of growth. 



VERMETUS. Cuv. ' 

 V. decussatus. Gruel, sp., p. 3T4o. , 



V. docussakis. Morch. Vermet., p. 2C. . . ■ 



I have a single specimen of only the regular part of this shell. It seems to agree 

 with the figures and descriptions, as well as with labeled specimens in the museum 

 of the Philadelphia Academy. 



PETALOCONCnUS. Lea. 

 p. sculp tu rat us. IT. C. Lea. Trans. Am. Pbil. Soc, Vol. IX, p. 230. 

 i'. JJomiiigeiisis, Shy. Quart. Jour., Vol. VI., p. 51, pi. 10, fig. 9. 



A comparison of extensive suites from both localities, proves beyond a doubt, the 

 identity of the species. 



