51-t DR G. S. BKADY ON 



than three-fourths of the length ; anterior extremity rounded and slightly sinuated 

 (scarcely notched) below the middle ; posterior margin narrow and rectangularly truncate ; 

 dorsal margin boldly arched, its hinder half scarcely at all curved ; ventral very strongly 

 arcuate. Seen from above, ovate, with wide obtuse extremities ; greatest width in the 

 middle, and equal to less than half the length. Surface marked with closely-set circular 

 punctations, and in old shells covered with a dense reddish-brown incrustation. Length 

 '9 mm. 



A shell presenting much the same general characters as the above, but smaller and 

 more angular in outline and with a more distinct notch, occurred in the same gathering. 

 This may perhaps be the male of P. robusta. I have had no opportunity of examining 

 in detail the soft parts of the animal, all my specimens being dried shells and containing 

 little or no remains of the internal structures ; but the fragments which I have seen agree 

 in general character with Cypridina. 



Habitat. — Vuna Point, Taviuni, low-tide pools. 



Pleoschisma moroides, n. sp. (Plate I. figs. 23, 24). 



Shell, seen from the side, subcircular, height equal to three-fourths of the length. 

 Anterior extremity wide, feebly rounded, almost flat, notch obsolete ; posterior narrower, 

 rounded, slightly sinuated above and below ; dorsal and ventral margins moderately 

 convex. Seen from above, broadly ovate, nearly equal in width throughout; extremities 

 broad and rounded, the anterior rather the narrower of the two ; lateral margins 

 moderately arcuate, width equal to four-sevenths of the length. Surface of the shell 

 minutely punctated, and in old specimens raised into circular bosses; colour dark brown. 

 Length 1*2 mm. 



Habitat. — Port of Noumea, dredged in 3-6 fathoms; Suva, inside reef; Levuka, 

 between tide-marks ; Vuna Point, Taviuni, between tide-marks ; Mango Island, fringing 

 reef. 



This curious species occurs not uncommonly in several of the localities above 

 mentioned, but I have been unable to obtain more than very fragmentary specimens of 

 the soft parts, which, so far as can be ascertained, closely resemble those of Cypridina. 



Pleoschisma reticulata, n. sp. (PL IV. figs. 11, 12). 



Shell, seen from the side, subcircular, greatest height situated in the middle and 

 equal to three-fourths of the length. Anterior extremity broadly rounded, slightly 

 sinuated below the beak, which is short and obtuse; posterior margin narrower, rounded, 

 obs'eurely angular at its junction with the dorsum, but rounded off below ; dorsal and 

 ventral margins boldly convex. Seen from above, broadly ovate, widest in the middle, 

 width equal to three-fifths of the length ; extremities obtuse, rounded, rather more 

 tapered in front than behind ; shell-surface smooth, marked with a delicate reticulated 

 pattern. Length '57 mm. 



