102 U.S. NATIONAL MUSEUM BULLETIN 2 95 



clear-cut to be named. The appendages of the two living specimens, 

 here termed variant A, appear to be fully mature, although no geni- 

 talia are observable. Their carapaces are identical in size and shape 

 to supposed juveniles in the subfossil assemblages; their inner lamellae 

 are present but very thin. 



Zabythocypris, new genus 



Etymology. — Greek za-, very, -\-Bythocypris. 



Type-species. — ^Bythocypris heterodoxa Chapman, 1910, p. 429, 

 pi. 56, fig. 20a, b. 



Diagnosis.— rCarapace t^ery much compressed, in lateral outline 

 subcircular to angularly suboval, left valve very much higher than 

 right valve; fused marginal zone wide with straight radial pore canals; 

 muscle-scar pattern bythocypridine. 



Male antenna without segmented sensory club, all distal setae 

 short; vibratory plate of first thoracic leg with 4 proximally segre- 

 gated featherless setae, 10 other setae of similar length, podomeres 

 and distal claw capable of being bent into a recurved hook; copulatory 

 organ without distinguishable copulatory tube; furca with 7 setae, 

 setae 2 and 4 longest. 



Species included. — Recent species, by original binomen: 



Bairdia exaltata Brady, 1880 

 ?Bythocypris heterodoxa Chapman, 1910 

 Zabythocypris ancipita, new species 

 Zabythocypris helicina, new species 



Affinities. — This genus is most similar to the Bairdiinae of any 

 of the Bythocypriinae in the relatively consistent soft-part anatomy. 

 Ecology. — A characteristic form at abyssal depths. 



Zabythocypris heterodoxa (Chapman), 1910 



Figures 5Qa-c, 57, 58 

 IBythocypris heterodoxa Chapman, 1910, p. 429, pi. 56: fig. 20a, b. 



Material. — A single adult male USNM 121617 collected living 

 at Anton Bruun cruise 11 station 95, west of Peru. 



A single adult valve of a more elongate and angulate forrri at Anton 

 Bruun cruise 8 station 410A in the Mozambique Channel. 



A fragmentary valve at Albatross station 2385 southeast of the 

 Mississippi Delta. 



Dimensions. — Adult male USNM 121617, left valve, length 

 1.79 mm, height 1.20 mm. 



Left valve USNM 121618, length 1.20 mm, height 0.95 mm. 



Distribution. — Chapman (1910) originally described this 

 species from three locations south of Funafuti at depths between 



