78 THE VOYAGE OF H.M.S. CHALLENGER. 



half the length ; seen from above, the outline forms a regular curve with a slight sinuation 

 towards either end, extremities equal and subacute. Surface of the shell smooth, slightly 

 undulated, and marked round the extremities and on the ventral margin with numerous 

 radiating haii'-like lines. Length, l-28th of an inch (-9 mm.). 



A few valves only belonging to this species were found in a dredging from off 

 Pernambuco (Station 120), lat. 8° 37' S., long. 34° 28' W., depth, 675 fathoms. From 

 these scanty materials it is impossible to describe the species fully, but there can be 

 little doubt of its distinctness from any recorded form. The valve shown at fig. 3, d, 

 may perhaps be taken to belong to the young of the same. 



[PL XV. fig. 3, a-d. a Left valve seen from side, h from above, c from front, 

 d right valve of a younger specimen. All magnified 50 diameters.] 



29. Cythere cytheropteroides, n. sp. (PI. XV. fig. 5, a-d). 



Valves seen from the side, subovate, much higher in front than behind ; the greatest 

 height equal to more than half the length ; anterior extremity broad, rounded, its lower 

 half armed with a series of broad, short, and blunt teeth, about twelve in number ; poste- 

 rior extremity produced, narrowed, and in some cases bearing two or three teeth, of 

 similar character to those of the anterior border ; dorsal margin gibbous in front, thence 

 sloping with a gentle curve to the hinder extremity, ventral slightly convex, sinuated in 

 front of the middle, seen from above, the outline appears to be subovate, widest behind 

 the middle, and with very thick, heavy extremities. The surface of the shell is smooth, 

 but bears a prominent rounded crest near the ventral margin. Length, l-32d of an inch 

 [■77 mm.). 



As with the preceding species, I am able only imperfectly to describe this shell. 

 Detached valves only were found, and very few of them ; these occurred in a dredging 

 from off the Cape of Good Hope, 150 fathoms (Station 142). 



[PI. XV. fig. 5, a-d. a Left valve seen from side, h from above, c from front, 

 d right valve seen from side. All magnified 50 diameters.] 



30. Cythere kergmlenensis, n. sp. (PL IV. figs. 16-18, and PL XX. fig. 1, a-f). 

 Carapace of the female, seen from the side, subreniform, higher in front than behind, 



greatest height situated in the middle, and equal to nearly two-thirds of the length ; 

 left valve much larger than the right ; anterior extremity well rounded ; posterior pro- 

 duced below the middle, and forming an angular squamous beak, which is often bordered 

 with a few small, blunt teeth ; dorsal margin evenly and boldly arched, highest in the 

 middle, ventral sinuated in the middle ; seen from above, oblong, ovate, widest in the 

 middle, and tapering evenly to the extremities which are equal and sharply acuminate ; 

 width scarcely equal to half the length; end view broadly ovate, broad below, and 

 tapering to the apex which is acute, sides very convex, base strongly keeled in the 



