INSTITUTE OF SCIENCE, PHILADELPHIA. 89 



directions, the upper ones downward to the right, the lower ones down- 

 ward to the left ; aperture quadrangular. 



Length, 1.7 inches; width of base, .3 inch. 



Caloosahatchie, abundant in the banks below Fort Thompson. 



Turritella oingulata, nov. sp. Fig. 15. ^ T < "^ 



Shell elevated, straight-sided ; whorls flat, faintly carinated inferiorly 

 by an obscurely beaded (or " roped ") line or band, which is followed 

 successively in the direction of the apex by two distinctly crenulated or 

 beaded lines, an obliquely and obscurely lined (barely elevated) band, 

 and a delicate terminal line ; the band above the two lines is more dis- 

 tinctly beaded along its base, appearing somewhat like a third crenulated 

 line ; aperture quadrangular. 



Length, 2.4 inches ; width of base, .5 inch. 



From the banks below Fort Thompson. 



Turritella mediosulcata, nov. sp. Fig. 16. 



Shell rapidly tapering, straight-sided ; whorls flattened, appearing 

 somewhat concave through the presence of a depressed median area or 

 band, which is bounded inferiorly by a fairly prominent beaded line ; 

 surface covered with numerous fine revolving lines, which above the 

 medial depression are cut obliquely (downward to the right) by obscure 

 rugations ; aperture quadrangular ; base flat. 



Length of fragment, 1.5 inches; width of base, .4 inch. 



A solitary specimen, from below Fort Thompson. 



Turritella subannulata, nov. sp. Fig. 17. 



Shell turreted, acuminate ; whorls angular, marked by a broad basal 

 impressed band or channel, which is ornamented with numerous delicate 

 revolving lines ; surface of the whorls above the channel longitudinally 

 plicated, with two well-defined submedial lines, and numerous finer lines, 

 as in the channel ; aperture rounded ; base convex. 



Length, 1.2 inches; width of base, .25 inch. 



Abundant in the banks below Fort Thompson. 



Cerithium atratum ? Born. 



Mus. Cass., p. 324, pi. ii, figs. 17, 18. 



I doubtfully refer to this species a solitary specimen found in the banks 

 below Fort Thompson. It is a somewhat more elevated shell than the 

 recent form, and its ornamentation also differs slightly ; but on the whole 

 its facies is very similar, and I am inclined to believe that among a selec- 

 tion of specimens individuals would be found to grade into the typical 

 C. atratum, which is itself a markedly variable species. The specimen 

 measures an inch and a half in length. 



