INSTITUTE OF SCIENCE, PHILADELPHIA. 53 



Lea's figure represents an immature and unrecognizable shell which may be 

 the young of a species like M. avena, and consequently I have thought it better 

 not to unite them. I have named the pure white form, variety immaailala, but 

 it differs from the type only in color. 



Marginella bella Conrad. 



Plate 4, figures 8 d, S e, and g a. 



Prunum bella {sic) Conrad, Am. Journ. Conch, iv. p. 67, plate 6, fig. 4, 1S68 ; Proc. Acad. 



Nat. Sci. 1862, p. 564 (name only). 



Virginia Miocene. Tampa silex-beds and orbitolite bed ; Caloosahatchie 

 beds. Recent, off the coast of North Carolina, living in 14 to 50 fathoms 

 sand. 



Among the original specimens of Conrad two species were represented, one 

 of which he had already named Af. siiccinea, and the present shell, which will 

 retain the later name. Among the pseudomorphs in silex from Ballast Point, 

 Tampa Bay, several varieties were represented. The most normal form is 

 that indicated by figure 9 a (Plate 4). Max. Ion. 8.0; lat. 4.5 mm. Specimens 

 from the Caloosahatchie, and the recent shells are often more strongly shoul- 

 dered than this. Among the Floridian specimens I find several which have 

 a sort of ridge at the shoulder, which I take to be abnormal. The absolute 

 size of the adult varies greatly, for the total length may be only five or six, or 

 as much as nine or ten millimeters, though the proportions are tolerably con- 

 stant. Figure 8 e represents a thinner, more oval form with a straighter outer 

 lip (Ion. 6.5 ; lat. 3.6 mm.), which may take the name of bellula. More ma- 

 terial may show it to be a distinct species. Variety inepta Dall (Fig. 8 d) is 

 smaller (5.5 Ion. by 3.0 mm. lat.), with a relatively higher spire, more evenly 

 tapered shell, and the outer lip less convex in the middle on the inside. 



The recent shell is yellowish or pinkish white with axially directed fine 

 opaque streaks hardly visible except on close scrutiny. They vary in size 

 even more than the fossil ones. 



M. bella was the type of Conrad's undefined group Porcellanella, which he 

 afterward abandoned. 



Marginella faunula n. s. 

 Plate 4, figure 9 b. 



Shell thin, ovate, with a rather pointed spire of some four or five whorls 

 Covered with a thin glaze of callus ; plaits four, subequal, thin, oblique, outer 

 lip little thickened, externally marginated, arcuate in the direction of its growth, 

 nearly straight in an axial direction ; callus on the body very thin. Max. Ion. 

 8.0 ; lat. 4.5 mm. 



Tampa silex-beds, rare. 



This shell recalls M. var. bellula in some of its features, while others remind 

 one oi M. fauna Sby. The habit of the shell is like the latter, while the form 

 is more like the former. 



