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



front, the outline is rounded, not much wider at the base than at the apex. Surface 

 beset mth angular pittings which, on the ventral aspect, are arranged in longitudinal 

 grooves. Length, l-52d of an inch ('49 mm.). 



Dredged off Booby Island (Station 187), in a depth of 6 to 8 fathoms. 



The specimens here noted differ somewhat from the types described in my mono- 

 graph of the Antwerp Crag Ostracoda, being less tapered in front when seen dorsally, 

 rounder and more narrowed behind when seen from the side. Nevertheless, the 

 Challenger specimens in general style and appearance so closely approximate to those 

 from the Antwerp Crag, that I do not think it safe to propose for them a separate specific 

 name. Two other fossil species, Cythere sithtriangularis, Speyer, and Cythere hastata, 

 Eeuss, Egger, are also very nearly allied, but without the opportunity of examining 

 authentic specimens, one cannot pronounce with certainty respecting them. Among 

 recent species Loxoconcha angiistata, Brady, Loxoconcha alata, Brady, and Loxoconcha 

 tnultifora (Norman), are all near relatives, but distinct. 



[PL XXIX. fig. 6, a-d. a Carapace seen from left side, 6 from above, c from below, 

 d from front. Magnified 50 diameters.] 



12. Loxoconcha alata, G. S. Brady (PI. XXVII. fig. 6, a-j). 



Loxoconcha alata, Brady, Ann. and Mag. Nat. Hist, ser. 4, vol. ii. (1868), \>. 223, pi. xiv. 

 figs. 8-13. 



Carapace of the female oblong, tumid ; seen from the side, subrhomboidal, equal in 

 height throughout, height equal to rather more than half the length ; anterior extremity 

 evenly rounded ; posterior oblique, produced above the middle into a short, blunt beak ; 

 dorsal margin straight, or very slightly hollowed, ventral almost straight ; seen from 

 above, the outline is irregularly lozenge-shaped, each valve having a conspicuous lateral 

 prominence behind the middle ; greatest width situated behind the middle, and equal to 

 about three-fourths of the length ; the extremities are broad and strongly mucronate, 

 the end view is somewhat trapezoidal in outline, its height and Avidth being about equal, 

 and its angles produced or gibbous. The surface of the shell is marked with numerous 

 small angular hollows, which, on the ventral surface, are disposed in longitudinal 

 grooves ; and towards the hinder extremity of the ventral margin on each valve is 

 a conspicuous, bluntly angular alseform process or tubercle ; there is also usually a 

 distinct polished tubercle over the anterior hinge-joint. Length, 1-5 5th of an inch 

 ("44 mm.). 



A considerable number of specimens of Loxoconcha cdata were found in a dredging 

 made off the reefs at Honolulu, in a depth of 40 fathoms. These difier somewhat from the 

 type-specimens which were got at Mauritius, but not so much, I think, as to warrant my 

 calling them by a new name. The Honolulu specimens are not nearly so sharp at the 



