REPORT ON THE OSTRACODA. 77 



rounded off. The sides of the valves are marked with irregularly scattered subrotund 

 excavations of variable size ; just within the ventral margin there is an elevated ridge, 

 and occasionally one or more indistinct longitudinal ribs on the middle of the valves 

 which are also slightly undulated transversely ; the hinge-line on the dorsal aspect 

 of the shell is distinctly depressed in the middle. Length, l-37th of an inch 

 {74 mm.). 



Dredged oS Nightingale Island, Tristan d'Acuuha, in 100 to 150 fathoms (Station 

 135) ; also in anchor-mud, from a depth of 6 fathoms, Stanley Harbour, Falkland 

 Islands (Station 316). 



The somewhat different forms figured in Plates XVI. and XXVI. I at first supposed 

 to belong to distinct species, but my impression now is that they cannot properly be 

 separated. The forms shown in PL XVI. occurred in the Falkland Islands only ; that 

 in PI. XXVI. in both localities. 



[PI. XXVI. fig. 6, a-d. a Shell seen from left side, b from above, c from below, 

 d from front. Magnified 50 diameters. PL XVI. fig. 3, a-d, represent similar views of 

 one of the Falkland Island forms. Magnified 60 diameters.] 



27. Cythere (1) serratida, n. sp. (PL XLIII. fig. 7, a-d). 



Valves compressed, oblong; seen from the side subreniform, rather higher in front 

 than behind, height equal to half the length ; extremities boldly rounded, anterior 

 smooth, posterior bordered with a series of very small distant spines ; dorsal margin 

 nearly straight, ventral deeply sinuated in the middle ; seen from above the valves are 

 compressed, ovate, and slightly sinuated in the middle of the lateral margin. Shell 

 smooth, or very partially and indistinctly marked with small circular impressed puncta. 

 Length, l-23d of an inch (1*1 mm.). 



Cythere serratida occurred in three di'edgings, but in each case only a very few 

 separated valves were found] it might, perhaps, more properly have been placed amongst 

 the CypridcB, but its real afl&nity must, with the scanty material at present available, be 

 merely conjectural : — Off" Culebra Island, West Indies, 390 fathoms (Station 24) ; off" 

 Canaries, 1125 fathoms (Station 85) ; and north of Tristan d'Acunha, 1425 fathoms 

 (Station 335). 



[PL XLIII. fig. ci^d. a, c, Eight valves (? young and old) seen from side ; h, d, the 

 same seen from below. Magnified 40 diameters.] 



28. Cythere i^yriformis, n. sp. (PL XV. fig. 3, a-d). 



Valves seen from the side, much higher in front than behind, all the margins perfectly 

 smooth ; anterior extremity broadly rounded, posterior also rounded, Ijut much narrower ; 

 dorsal margin boldly arched, highest in front of the middle, and sloping steeply back- 

 wards, ventral margin nearly straight, greatest height equal to considerably more than 



