REVISION OF RECENT BAIRDIIDAE 77 



Dimensions. — Adult male USNM 121344, left valve, length 

 1.28 mm, height 0.81 mm; right valve, length 1.24 mm, height 

 0.77 mm. 



Affinities. — The terminal hinge dentition is less marked in this 

 form than in the more typical shallow-water species of Bairdoppilata; 

 however, it is clearly visible on the Challenger paratype specimens. 

 The lectotype specimen is more highly and angularly arched dorsally 

 than the paratypes, and its hinge has not been seen. The Eltanin 

 specimens are very slightly smaller and more elongate than the 

 paratypes. 



The less conspicuous hinge dentition, more convex lateral outline, 

 and short, nearly straight copulatory tube are characters shared by 

 B. (B.?) simplex (Brady) and in part by B. (B.?) hirsuta. For these 

 species another subgeneric category probably should be established. 



Distribution. — Kerguelen I., Macquarie I., Prince Edward I.; 

 reported by Brady (1880) from Tristan d'Acunha and Bass Strait. 

 Subsequent reports of this species are numerous but mostly uncon- 

 vincing. 



Bairdoppilata {Bairdoppilatal) simplex (Brady), 1880 



(Figure 42) 



Bairdia simplex Brady, 1880, p. 51, pi. 7: fig. la-d. 

 Nesidea labiata Muller, 1908, p. 99, pi. 14: figs. 1-6. 



Material. — A left and a right valve, of the same specimen, in 

 Challenger slide no. 142, British Museum (Nat. Hist.) cat. no. 81.5, 

 labeled station no. 151, off Heard I., depth 75 (fms); designated 

 lectotype by Puri, Hulings, and Benson (MS.). 



One male living at Eltanin station 1345; one male and one female 

 hving and one empty carapace at Eltanin 418; 25 subfossil specimens 

 at Eltanin stations 1345, 1346; 4 subfossil specimens from GIL 615, 

 South Africa. 



Dimensions. — Adult female USNM 121347, right valve, length 

 1.97 mm, height 0.97 mm. 



Adult male specimen USNM 121348, left valve, length 1.62 mm, 

 height 0.96 mm; right valve, length 1.64 mm, height 0.92 mm. 



Distribution. — Off Heard I.; Palmer Peninsula, Gauss Station, 

 Antarctica; South Indian-Antarctic Basin; ? False Bay, South Africa. 



Affinities. — The Eltanin specimens are slightly larger, more 

 angulate in outline and more inflated than the Challenger valves; 

 their terminal hinge dentition is much weaker than that of the lecto- 

 type, with no visible teeth in the right valve and only obscurely 

 serrate grooves in the left. 



The anterodistal antennal claw is not as long or thick as the distal 

 claw, although sufficiently developed to be considered bairdoppilatan. 



