244 MR..W. H. PEASE ON NEW SPECIES OF SHELLS. [NoV. 11, 



The only species with which this can be compared is the P. tri- 

 carinata, Val. They agree in the peculiar form of the sinus, and 

 differ in that respect from all other species of the family. Our spe- 

 cies is, however, more slender, and bears a less number of keels. 



Marginella cylindrica. 



Shell cylindrical, smooth, polished, white ; last whorl ornamented 

 on the back with broad yellowish bands, a spot of darker colour at 

 the base. Aperture linear ; outer lip simple, slightly expanded at 

 the base, and spreading a short distance over the spire, at its junc- 

 tion posteriorly, by a callosity ; inner lip four-plaited at the base., 



Hab. Kingsmill Islands. 



COLUMBELLA PUSILLA. 



Shell small, fusiform, smooth, transversely striated at the base. 

 Whorls seven, slightly convex ; aperture oblong ; canal rather wide, 

 and slightly recurved ; outer lip thin, thickened externally, denti- 

 culate within, and sinuated near its junction posteriorly ; inner lip 

 plicately thickened. Colour light fulvous or white, with irregular 

 longitudinal, somewhat reticulated, chestnut-brown lines. At the 

 upper part of the whorls, lines much less distinct and smaller ; last 

 whorl encircled by a narrow white band. 



Hah. Kingsmill Islands. 



SiSTRUM AFFINE. 



Shell ovate, thick, stout, longitudinally and transversely ribbed, 

 interstices deeply excavated ; longitudinal ribs rather broad, obtusely 

 noduled, nodules oblong ; transverse ribs smaller, and striated trans- 

 versely, interstices filled by two or three irregular-sized ribs or 

 ridges. Aperture oblongo-ovate ; folds on the inner lip faint. Co- 

 lour black ; transverse ribs white between the nodules ; edge of lip 

 and base black ; columella purplish brown. 



Hab. Kingsmill Islands. 



The above species belongs to a group of which the 8. tuberculatum, 

 Blalnv., may be considered the type. Our species, however, differs 

 from that in being much more deeply engraved throughout, in the 

 longitudinal ribs being more distinct, and the transverse striae form- 

 ing ribs or ridges. 



AviCULA RADIATA. 



Shell obliquely oblong, rather narrow, and somewhat curved, acu- 

 mlnately ridged, upper side angulate ; posterior wing slender and 

 elongate, of nearly the same length as the shell. Colour black, 

 finely rayed with dark chestnut-brown, and covered with a brown, 

 serrated, festooned epidermis. 



Hah. Kingsmill Islands. 



AviCULA brunnea. 



Shell oblique, rather oblong ; posterior wing slender and elongate, 

 finely striated concentrically, and somewhat obsoletely radiately 



