1895 PROCEEDINGS OF THE NATIONAL MUSEUM. 41 



spirals, whicb are more conspicuous than the riblets which they over- 

 run. In full-grown specimens the diameter of the base is proportion- 

 ately greater than in T. dislocata, and the surface is less polished. The 

 young T. Indenta resemble an exceptionally stout T. protexta., Conrad. 

 The variety, which, when well developed, often seems perfectly distinct 

 from typical T. dislocafa, nevertheless grades insensibly into the latter 

 in a large collection from one locality, and it can not be regarded as a 

 mutation of more than v. rietal rank. 



renus CONUS, Linnaeus. 



The species of this genus are separated when belonging to the recent 

 fauna largely by their color-pattern, and m the absence of this aid 

 they are doubly ditticult to discriminate. In general the rule that 

 local fauniB are derived from preexisting fauna' of the same general 

 region is a good guide, and a careful comparison of the fossils w^ith 

 the recent types will often assist materially in determining the rela- 

 tions of fossil forms. The identifications which travel to distant 

 fauiuTe for representatives — as, for instance, the Indo-Pacific fauna for 

 Haitian fossils — are usually wrong, and all Gabb's identifications of 

 this sort will be modified by further and more careful study. Analogous 

 characteristics are often purely dynamic in forms of different lineage 

 subjected to similar conditions in widely distant localities. Where 

 modern faun;e differ in the races of any genus which they contain, the 

 antecedent fossils in the same regions are not likely to be much more 

 nearly related. 



The Mediterranean and African cones belong to groups which are 

 not effectively represented in American waters; hence it is probable 

 that none of the identifications of American with European Tertiary 

 cones have the weight of probability m their favor. The same type 

 may be represented in both faunae, but this is only exceptionally the 

 case, and is not to be taken for granted. 



In de Gregorio's useful but rather slipshod work on the Alabama 

 Eocene fossils the common Conns sauridcns of Conrad is referred to 

 C. ilivers'formis of Deshayes, an Eocene cone of the Parisian basin. 

 They are in fact very simil-ar species, but if identical, G. smiridens, being 

 the older name, must be applied to the French species and not the 

 French name to the American species. I think, however, the two 

 species are not identical. (J. dirersiformis is a much thinner and 

 lighter shell, with a proportionally wider aperture, and does not show 

 the remarkable plait at the end of the pillar, the formation of which 

 announces maturity in C. sauridens. The latter species, though rather 

 rare at Claiborne, is only varietally se[)arated from the Jacksonian 

 G. tortilis and the Vicksburgian G. alvcatus, while the old 3Iiocene 

 G. plnniceps, Heilprin, forms the culmination of the series. Very young 

 G. saiirUlcns (like many other immature cones) show small nodules at the 

 shoulder or just below it; these are the G. parvus, H. C. Lea. G. pro- 

 tracttis, Meyer, and Co pulcherrimas, Ileiiprin, with a probably new 



