MOLLUSCA — HEDLEY AND MAY. 



Arcularia mobilis, sp.nov. 

 (Plate xxiii., tig. 16). 



Shell small, rather thin, conical. Whorls well rounded, thus 

 appearing a little contracted at the sutures, in number five and a 

 half, including a smooth two-walled protoconch. Colour dull 

 white, with irregular brown spots, which tend to disposal in 

 spiral bands. Sculpture : the whole shell is neatly engraved with 

 sharp narrow grooves, about ten to the penultimate and eighteen 

 behind the aperture. Wave-like radial ribs, about a dozen to a 

 whorl, are usually more conspicuous above, and become obsolete 

 on the last whorl. Aperture oblique, round, strongly varixed 

 without, crenulated within to correspond with the external 

 sculpture, a slight tubercle posteriorly. (.'anal short and strongly 

 bent. Length, 7 ; breadth, 4 mm. 



Numerous specimens. "We cannot recall any near all) 7 of this 

 very variable shell. 



Var. costata. 



(Plate xxiii., fig. 1 7). 



In this form, which perfectly intergrades with the type, the 

 spiral sculpture is suppressed, and a radial sculpture is assumed 

 of close, strong rounded ribs, about twenty to a whorl, which 

 traverse the whole shell perpendicularly. If the intermediates 

 were unseen, the extreme would be readily granted specific rank. 



Trophon oolumnakius, sp.nov. 

 (Plate xxiv., fig. 22). 



Shell of medium size, elongate, roughened by the profuse decora- 

 tion. Colour pale yellow, with brown on the apex, a basal and 

 a sutural band. Whorls nine, including a smooth conical proto- 

 conch of two and a half whorls. Sculpture : thin projecting 

 varices, nine to a whorl on the larger whorls, ascend obliquely 

 and continuously from whorl to whorl. These varices are 

 scalloped by the passage of the spirals, and develop sharp points 

 on the shoulder; on the hase they degenerate to mere scales. The 

 spirals amount to twelve on the body whorl, and to three or four 

 on the upper whorls ; they are crowded on the base, but separated 

 on the shoulder by flat interstices of equal or greater breadth. 

 A secondary microscopic sculpture of faint radial threads, and 

 still fainter spiral scratches, appears between the varices. A per- 



