OSTRACODA COLLECTED IN THE SOUTH SEA ISLANDS. 511 



ginate in the middle. Surface rugged, irregularly undulated and pitted ; a longitudinal 

 alaeform process just within the ventral margin, but not strongly developed. Length 

 "43 mm. 



Habitat. — Sava-Sava Bay, Vanua Levu, 4 fathoms. 



Cytheropteron longicaudatum, n. sp. (PI. III. tigs. 18, 19). 



Shell, seen from the side, oblong, nearly equal in height throughout, height equal to 

 about half the length. Anterior extremity obliquely rounded, the obliquity looking 

 upwards ; posterior produced into an acutely- tapering median triangular beak of great 

 length ; dorsal margin convex before and behind, with a very deep median sinus ; ventral 

 convex and rather sinuous, terminating in an abrupt angle behind. Seen from above, the 

 outline is hastate, widest near the middle, width equal to two-thirds of the length ; from 

 the widest point the sides converge with a bold convexity forwards, forming a lancet-shaped 

 front ; posterior extremity forming a wide, tapering and very acute triangular process. 

 Surface of the valves deeply furrowed across the middle, bearing also a more or less 

 distinct central tubercle in front of the groove, and several obscurely radiating ribs with 

 small fossse in the interspaces. Length '57 mm. 



Habitat. — Suva, mud-flats ; Levuka, between tide-marks ; Sava-Sava Bay, Vanua 

 Levu, 4 fathoms ; Rambe Island, between tide-marks ; Loma-Loma, in shore-sand. 



Cytheropteron guttatum, n. sp. (PL IV. figs. 29, 30). 



Shell, seen from the side, subovate, highest in front of the middle, height equal to 

 about two-thirds of the length. Anterior extremity wide and rounded, posterior sub- 

 truncated, slightly produced below the middle ; dorsal margin well arched, obscurely 

 angular over the anterior hinge ; ventral straight, slightly sinuated in front and behind ; 

 lateral ala moderately prominent, and rounded off at each extremity. Seen from above, 

 the outline is lozenge-shaped, widest behind the middle, width equal to two-thirds of the 

 length ; anterior extremity very obtuse, rounded ; sides sloping with a bold convexity 

 backwards, and near the posterior extremity dipping suddenly in a hollow curve to the 

 extremity, which is wide and truncate, but narrower than the anterior. Surface smooth, 

 marked throughout with closely-set circular, impressed puncta ; hinge-tubercle polished 

 and conspicuous. Length '5 mm. 



Habitat. — Noumea, dredged in 2-6 fathoms. 



Cythcropteron (?) trilobites, n. sp. (PI. III. figs. 22, 23). 



Shell, seen from the side, oblong, quadrangular, highest in front, height equal to 

 about half the length. Anterior extremity wide, obliquely subtruncated, only moderately 

 rounded ; posterior produced above the middle into a triangular beak, excavated below 

 the middle ; dorsal margin sloping rather steeply from the front, and showing two deep 

 angular sinuations, one in front of and the other behind the middle ; ventral nearly 



