10 PROCEEDINGS OF THE NATIONAL MUSEUM vol. i21 



Eyes: Lateral eyes large; about 19 ommatophores visible in side 

 view, all except 2 divided by a suture into 2 parts (fig. 3m). Medial 

 eye large, pigmented (fig. 3i)- 



Frontal organ (fig. 3i): Elongate, 2-jointed with short spines on 

 distal half of 2nd joint and subterminally on basal joint. 



Description of female. — Shell (figs. 4a-i): lateral outline more 

 ovoid than male (fig. 4a); hinge structure (fig. 4g) selvage similar to 

 male; adductor muscle scars (figs. 4a,h) more anteriorly and ventrally 

 located on shell than on male; rostrum narrower and incisure shallower 

 than on male; UTegular polygons on surface of shell subdivided by 

 minute polygons larger than on male shell and visible under low 

 magnification (fig. 4/). Inner lamella with parallel striations on 

 antero ventral part; 9 long hairs with secondary spines forming row 

 on inner lamella behind rostrum (figs. 46, c) ; inner lamella below rostral 

 incisure with small hair followed by wide space and then 5 hau's (fig. 

 4e); posteroventral part of inner lamella with at least 21 hairs (fig. 4i); 

 lateral surface of rostrum and anterior part of shell with numerous 

 hairs with blunt ends (fig. 4d). 



Dimensions: Specimen no. 1 greatest length 1.06 mm, greatest 

 height 0.86 mm; specimen no. 2 greatest length 1.03 mm, greatest 

 height 0.73 mm. Graf (1931, p. 38) gives length as 0.90 mm and 

 1 .00 mm and height as 0.70 mm. 



First antenna (fig. 4j) : First and 2nd joints with surface hairs. 

 Second joint with 3 bristles, 1 dorsal, 1 ventral, and 1 lateral. Third 

 joint with 1 ventral bristle distally and 1 short bare bristle and 1 long 

 hirsute bristle on dorsal margin; ventral margin with short spines. 

 Fourth joint with 2 dorsal subterminal bristles and 1 short and 3 long 

 ventral subterminal bristles; ventral margin with short spines. Fifth 

 joint with stout ventral terminal bristle with filaments. Si.\th joint 

 with medial bristle distally. End joints with 1 short bristle and 2 

 long bristles without filaments and 4 long bristles with filaments. 



Second antenna (figs. 4k, I) : Protopodite subtriangular without 

 transparent rim. Exopodite (fig. 40 with 9 joints; 1st joint elongate 

 with small medial spine; 2nd to 9th joints trapezoidal without basal 

 spines; distal margins of 2nd to 5th joints with comb of slender spines; 

 2nd and 3rd joints with bristles without natatory hairs or marginal 

 denticulations; 4th to 8th joints with bristles having natatory hairs 

 and margmal denticulations; 9th joint with 2 short bare bristles and 

 2 subequal long bristles with natatory hairs and marginal denticula- 

 tions. Endopodite (figs. 4k,l) with 2 joints; basal joint with long stout 

 bristle with wreath of long hairs near middle, and 3 to 5 short bare 

 bristles; distal joint elongate with small spine at tip and long stout 

 terminal bristle with wreaths of long hairs near middle and short 

 distal spines. 



