OSTRACODA COLLECTED IN THE SOUTH SEA ISLANDS. 509 



equal to half the length. Anterior extremity rounded and somewhat oblique, posterior 

 having a broad median beak, above which it slopes steeply and with a slight convexity to 

 the dorsum ; below it is obliquely truncated, the obliquity looking downwards, and 

 rounded off at the ventral angle ; dorsal margin straight in front, but elevated behind, 

 and forming an angular hump ; ventral sinuated in the middle. Seen from above 

 irregularly lozenge-shaped, compressed, widest near the middle, more than twice as long 

 as broad; anterior extremity broad, only slightly rounded; posterior very wide, truncated, 

 and having a blunt median emarginate process ; sides converging gradually and with a 

 somewhat sinuous outline to the front, and deeply excavated towards the posterior 

 extremity. Shell-surface very rugged, with irregular but not very prominent flexuous 

 longitudinal ribs, which are connected transversely at intervals so as to form a rough reti- 

 culation ; the anterior hinge-tubercle is large, polished, and conspicuous. There are two 

 distinct forms of this shell, probably sexual. The second form differs from that described 

 above, in having a much more regular surface with less rugged sculpture, a more even out- 

 line, and no angular hump on the dorsum. This I take to be the female. Length "6 mm. 

 Habitat. — Suva, reef ; Levuka, between tide-marks ; Loma-Loma, in shore-sand ; 

 Apia, Upolu, reef and shore-pools. 



Cytherura entomon, n. sp. (PI. III. figs. 26, 27, 27a). 



Shell, seen from the side, subrhomboidal, height equal to rather more than half the 

 length. Anterior extremity very oblique, slightly rounded, the obliquity looking upwards ; 

 posterior broadly beaked above the middle, the apex of the beak emarginated, below this 

 the extremity slopes sharply away backwards, forming a continuous line with the ventral 

 margin; dorsal margin rugged, broken by numerous small blunt projections; ventral 

 convex. Seen from above, the outline is jagged and very irregular, more or less ovate, 

 obtusely pointed in front, more produced and acute behind, width equal to about one 

 half the length ; behind the middle there is on each side a conspicuous club-like process 

 directed transversely outwards. Shell-surface marked with indistinct oblong impressions, 

 their long diameters directed transversely ; towards the posterior extremity there is in 

 some specimens a transverse series of about 5 or 6 backwardly-directed spines. Length 

 '5 mm. 



Habitat. — Port of Noumea, 3-6 fathoms ; Sava-Sava Bay, Vanua Levu, 4 fathoms. 



The description applies to the largest and most rugged specimens; but others occur 

 in which the surface is not nearly so rough, the lateral outline more regular, the strong, 

 transverse processes being absent, and the posterior extremity produced in a linear fashion. 

 A shell of this kind is represented at fig. 27a. 



Cytherura scutellata, n. sp. (PI. III. figs. 30, 31). 



Shell, seen from the side, subrhomboidal, highest in the middle, height equal to more 

 than half the length. Anterior extremity rounded, placed entirely below the middle line ; 



