314 TRANSACTIONS OF THE WAGNER FREE 



ing whorl ; above this are four narrow less prominent keels or elevated spirals, 

 with much wider about equal interspaces, which on the later whorls carry a 

 fine intercalary spiral line ; the surface is polished, but shows traces under the 

 lens of microscopic spiral striae; in front of the main carina are one or two 

 elevated spirals between it and the almost invisible suture; the base inside of 

 the sutural line is distantly spirally sculptured and rather convex ; the aper- 

 ture is subquadrate, the pillar arched, thin, and. twisted so as to offer a mi- 

 nutely pervious axis; the throat is provided with strong sharp lirae independ- 

 ent of the sculpture. Lon. of shell "j"] ; max. diam. of base 17 mm. 



This is a very elegant and distinct species which in some of its features 

 faintly recalls T. imbricataria Lam. of the Parisian Eocene. 



The American species which is nearest to it in form, though a much 

 smaller shell, is the unfigured T. alticostata from the Miocene of Virginia and 

 Maryland. This has been identified from Conrad's type by Mr. Harris, but it 

 has rounded, close-set threads and is only about half the size of the Chipola 

 species. T. alticostata will probably turn out to be a carinated variety of T. 

 variabilis. 



It occasionally happens that the main carina in T. siibgnindifera is no larger 

 than the others, in which case, of course, the whorls have a more rounded ap- 

 pearance. But these specimens are rare compared with the carinated, which 

 seems to be the normal form. It is the only fossil species here referred to with 

 sharp lirse in the throat; the others have the throat quite smooth except in 

 cases where the sculpture is reflected by sulci in the interior of the aperture. 



Turritella subannulata Heilprin. 

 Plate 16, figures i, 2, 3, 4. 

 T. subatmulata Hp., Trans. Wagn. Inst. i. p. 89, pi. 8, fig. 17, 1887. 



Abundant in the Pliocene marl of the Caloosahatchie and also found in 

 the older Miocene of the Chipola beds. Burns ; the Pliocene of Shell Creek, 

 Florida, and Tilly's Lake, Waccamaw beds. South Carolina, Willcox and 

 Johnson; also living (var. acropord) from Cape Hatteras to the Antilles 

 (Grenada) and Vera Cruz, Mexico, in 3 to 413 fathoms. 



This is a very remarkable species, which has been collected in such 

 abundance as to throw a flood of light on the variations which may occur in 

 a single species under essentially similar conditions, while the same species 

 exhibits such an inflexibility of constitution as to persist, practically un- 

 changed, for such an immense period as is implied by the interval between the 

 deposition of the old Miocene Chipola beds and the present epoch. The 

 figures on Plate 16 represent extremes which no one who did not possess in- 

 termediate gradations would for a moment hesitate to regard as " good 

 species," while no doubt the gentlemen who amuse themselves and impede 

 study by such work as is characteristic of the so-called "nouvelle ecole," 

 would find fifty or sixty other " species " among the material before me. 



