INSTITUTE OF SCIENCE, PHILADELPHIA. 153 



not pervious, but with its distal end open and rarely perfect, turned toward 

 the axis; whorl behind the shoulder irregularly flattened, appressed, but not 

 much expanded at the suture ; from the spine at the shoulder to the whorl 

 behind the varix is sometimes filled in by a thin shelly plate, and sometimes 

 the plate is absent or obsolete ; tubes moderate, situated midway between the 

 varices or nearer the preceding varix, extending outward and backward ; canal 

 short, broad and flattened, with a small perforation; spiral sculpture of a lew 

 low ridges extending from the vicinity of the aperture to the summit of the 

 varix, where they appear as serrations or abortive spines, but are obsolete be- 

 hind the varix, or they may be absent altogether ; aperture subovate, simple, 

 with a plain elevated rim. Max. Ion. of figured specimen 14.5 ; diam. 9.5 ; of 

 a larger but less perfect one, 22 x 12 mm. 



The older specimens have a proportionally longer canal and less expanded 

 varices, which makes them appear more slender than the young ; a good deal 

 of difference in the appearance of the specimen results from the presence or 

 absence of the elevated plate between the spine and the preceding whorl 

 across the shoulder. This feature seems to be entirely inconstant, though I 

 found it difficult to believe this until I found it inconstant at different stages 

 of the same specimen. 



This species, as might be expected, is nearest to the Miocene T. acuticosta 

 Conrad, which has thicker and rounder varices, with a small, stubby, triangu- 

 lar spine at the shoulder, and an intervarical rib extending forward from the 

 base of each tube, where T. floridamis is flattened. The nucleus is not pre- 

 served in any of my specimens of floridamis. Among recent species, T. 

 tetraptcrus Bronn is nearly related to T. floridamis, though perfectly distinct. 



Subfamily PURPURIN^. 



Genus RAP ANA Schumacher. 



Many heterogeneous forms, including Ecpliora, have been referred to this 

 genus because they happened to have a flaring umbilicus. That feature 

 is the mechanical result of certain factors in the form of the shell which do 

 not, necessarily, have anything to do with its systematic relations. I have 

 already referred to Stenomphalus of Sandberger, which has been supposed to 

 be congeneric with Ecphora. As far as one can judge from the figures alone, it 

 is merely a Rapana, to which genus (typified by R. bcsoar Linne) it should 

 be referred. 



Rapana tampaensis n. s. 



Ballast Point silex-beds, Tampa Bay, Florida. 



Shell rather small, short-spired; last whorl much the largest; spiral 

 sculpture of eight or nine primary ridges, elevated and square-sided, of which 

 one is near the suture, two others (a little larger) with subequal interspaces in 



