108 XJ-S. NATIONAL MUSEUM BULLETIN 295 



Affinities. — The specimen illustrated by Chapman is probably 

 a juvenile, because of its nearly circular lateral outline. The southeast 

 Pacific and Mozambique Channel specimens almost certainly belong 

 to different subspecies. 



Zabythocypris exaltata (Brady), 1880 



Bairdia exaltata Brady, 1880, pi. 9: fig. 2a-d. 



Material. — Challenger lectotype specimen in slide 132, British 

 Museum (Nat. Hist.) cat. no. 81.5, from station 218, north of New 

 Guinea, at 1075 fms. 



Affinities. — This relatively thick-shelled species with nearly 

 circular lateral outline approaches most closely to the Bairdiinae of 

 all species of Zabythocypris, and its subdivided muscle-scar pattern 

 is an excellent one on which to trace the homologies between individual 

 scars of the bairdiine and bythocypridine patterns. 



Zabythocypris ancipita, new species 



Figure 59 



Etymology. — Latin anceps, two-sided, double, ambiguous; from the 

 conspicuous dimorphism. 



Type-specimens. — Holotype USNM 121620; para types USNM 

 121621-121624. 



Type-locality. — Anton Bruun cruise 7 station 363 G. 



Diagnosis. — Carapace thin but very large, expanded medially and 

 extremely compressed marginally; lateral outline of one form ap- 

 proaching rectangular, especially in right valve, dorsal margin very 

 gently rounded and so much compressed that dorsal and lateral 

 carapace lamellae are fused together, with pore canals traversing 

 this fused zone just as in the marginal area; second form much less 

 symmetrical in lateral view and more rounded, with steeply sloping 

 posterodorsal margin, narrowly rounded posteroventral margin, an- 

 terior margin broadly rounded, venter slightly concave, dorsal mar- 

 ginal area open rather than fused. 



Material. — Subfossil specimens only; subrectangular form found 

 &t Anton Bruun stations 361B (1), 363G (8), 363J (14), and 363K (4) ; 

 asymmetrical form found at Anton Bruun stations 360B (2), 363 G 

 (13), 363J (19), and 363K (15) [numbers in parentheses indicate 

 number of specimens in each collection]. 



Dimensions. — Holotype USNM 121620, subrectangular left valve, 

 length 1.58 mm, height 1.15 mm. 



USNM 121621, subrectangular right valve horn. Anton Bruun 363 G, 

 length 1.59 mm, height 0.94 mm. 



