1881.] ON NEW SHELLS FROM LAKE TANGANYIKA. 559 



versely lirate, the points of intersection of the lirae and costse being 

 more or less granular. The aperture is ovate, and not produced into 

 a canal at the base as in Tiphobia ; and the colamella and upper 

 extremity of the outer lip are connected by a thickish callosity. This 

 division (Paramelania) will also include the Melania nassa of Wood- 

 ward, so remarkable for its great variability. 



Paramelania, subgen. nov. 



Shell solid, ovate-conical, imperforate, longitudinally ribbed and 

 transversely lirate, covered with a thin epidermis. Aperture ovate, 

 entire, indistinctly effuse at the base. Last whorl sometimes slightly 

 prolonged inferiorly. Peristome thick, margins joined by a callosity. 

 Operculum like that of Tiphobia. 



Paramelania damoni. 



Shell solid, imperforate, ovate turreted, white, covered with an 

 olive-brown epidermis, prettily sculptured with fine yet distinct wavy 

 lines of increment, and more or less distinct transverse impressed 

 striae. Whorls 10, very concave at the upper part, the concavity 



Fig. 1. 



Paramelania damoni. 



occupying about one third of the whorl; concavity smooth, merely 

 exhibiting the epidermal sculpture ; rest of the whorls coarsely 

 plicated and spirally ridged. Plicae rather acute, about 12 in 

 number on the penultimate whorl, a little oblique on the last, and 

 becoming obsolete about the middle. Spiral lirae rather slender, 

 equal, continuous on and between the plicse ; 4 upon the upper 

 volutions, and about 14 on the last. The uppermost, which defines 

 the upper end of the costae, is produced into very short hollow scales 

 or spines upon the ribs ; and the second and sometimes the third have 

 the same character in a less marked degree. Aperture obliquely 

 ovate, occupying about half the length of the shell, covered with a 

 slight callous deposit far within, not quite obscuring the external 



