REPOET ON THE OSTRACODA. • 133 



beak ; superior margin moderately arched, inferior straight ; seen from above, the outline 

 is oblong-ovate, more than twice as long as broad, widest near the front, tapering abruptly 

 towards the obtusely-pointed anterior, and gradually towards the broadly mucronate 

 posterior extremity ; end view hexagonal, with concave margins ; valves marked in the 

 middle of the lateral aspect with a longitudinal flexuous ridge and on the ventral surface 

 with numerous longitudinal ridges, the other portions of the surface being irregularly and 

 coarsely reticulated with prominent ribs. Length, l-60th of an inch ("42 mm.). 



This very well-marked species occurred in a dredging from Balfour Bay, Kerguelen 

 Island, in 20 to 50 fathoms. Its nearest known ally is probably Oytherura clathrata, 

 Sars, with which it closely agrees in style of surface-sculpture though quite different in 

 proportions and general contour. 



[PI. XXXII. fig. 6, a-d. a Carapace seen fromleft side, h from above, c from below, 

 d from front. Magnified 75 diameters.] 



6. Oytherura clavata, n. sp. (PI. XXIX. fig. 7, a-d). 



Carapace, as seen from the side, oblong, nearly equal in height throughout, length 

 equal to twice the height ; anterior extremity well rounded, posterior produced in the 

 middle into a short and broadly truncated beak ; dorsal and ventral margins parallel and 

 nearly straight ; seen from above, the outline is subcuneate, widest behind, more or less 

 constricted in the middle (the constriction more marked in the female), extrerrtities 

 centrally mucronate, the anterior broadly rounded, posterior subtruncate, width about 

 equal to the height ; end view subcircular, broad at the base and somewhat angulated at 

 the apex. Surface of the shell marked with numerous delicate longitudinal anastomosing 

 ridges ; each valve has also a wide transverse groove or depression across the middle. 

 Length l-40th of an inch ('65 mm.). 



A considerable number of specimens of Oytherura clavata were found in a dredging 

 from Stanley Harbour, Falkland Islands, — 6 fathoms. The species is not unlike 

 Oytherura gibba (Mliller), but is much more wedge-shaped when seen from the dorsal or 

 ventral aspect. Some specimens have a much more distinct transverse groove than 

 others, as shown in the two figures b, c. The difference is probably sexual. 



[PI. XXIX. fig. 7. a-d. a Carapace seen from left side, b from above, c from below, 

 d from front. Magnified 50 diameters.] 



7. Oytherura mucronata, n. sp. (PL XXXII. fig. 9, a-d). 



Carapace, as seen from the side, subrhomboidal, highest about the middle, height equal 

 to fully half the length ; anterior extremity obliquely rounded, posterior produced into a 

 large tapering central beak ; dorsal margin forming a flattened arch, ventral convex, 

 slightly sinuated in front of the middle ; seen from above the outline is compressed-ovate, 

 widest in the middle and tapering evenly to the extremities, the anterior being sub- 



