AND OSTKACODA COLLECTED ROUND FUNAFUTI. 437 



The valves found in the present dredgings are generally typical, but the 

 alar beak is sharply pointed and prolonged instead of obtusely rounded as in 

 Brady^s ' Challenger ' specimen. 



Occurrence.— 8ta. 10, 1485 fms. ; 13, 1050 fms. 



Gytheroptbron abyssorum, G. S. Brady. 



Cytheropteron abyssorum, G. S. Brady ('80), p. 138, pi. 34, figs. 3 a-d. 



Described by Brady from one locality only, in the Southern Ocean, S.W. 

 of Tasmania, 2600 fathoms. 



Occurrence, — Sta. 11, 1417 fms. ; 13, 1050 fms. Separate valves not 

 uncommon. 



Genus Bythocythere, G. 0. Sars. 



Bythocythere retiolata, sp. nov. (Plate 57. figs. 26 a, b.) 



Description. — Carapace elongate ; seen from the side compressed, subovate ;- 

 of nearly equal width throughout, height less than one-half the length ; 

 anterior extremity strongly arched, dorsal line nearly straight and excavate 

 posteriorly, ventral border concave in the upper third, then widely convex 

 and curving backwards to meet the posterior prolongation ; median area of 

 valve tumid, highest towards the ventral region and posterior, sloping away 

 to the anterior border ; a deep, curved sulcus parallel with and just within 

 the anterior margin. Median area deeply excavated by a transverse fold or 

 sulcus, extending, a third away from the ventral, to the dorsal margin. 

 Surface-ornament consisting of a distinct raised polygonal network. Edge 

 view subovate, compressed at the extremities. 



Length '833 mm. ; height '312 mm. ; approximate thickness of 

 carapace "3 mm. 



Occurrence. — Sta. 13, 1050 fms. 



Bythocythere tuberculata, sp. nov. (Plate 57. figs. 27 a, h.). 



Description. — Carapace subovate, compressed at the extremities ; highest 

 at the anterior, attenuated posteriorly. Seen from the side, elongate, sub- 

 quadrangular, dorsal edge straight, and meeting the evenly rounded anterior 

 margin at a sharp angle ; antero-ventral angle rounded and widely curved 

 along the ventral line ; posterior extremity produced to a broad point. 

 Surface of valve with a rounded prominence a little in front of the median 

 area on the dorsal margin, behind which is a curved transverse depression ; 

 there is also a subventral ridge which carries a strong stout spine projecting 

 outwards and downwards. Surface coarsely punctate and covered with 

 strong prickles. Anterior margin denticulate. A narrow flange exists along 

 the greater part of the ventral border. 



