988 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxvi. 



Seen from the side (fig-. 1) the shell is highest in its iintcrior one- 

 third, the highest point being decidedly of a hump-like appearance. 

 The anterior end is more evenly rounded than the jjosterior, wider, 

 and is armed on the outer lip of both valves with a roAv of from 9 to 

 11 semitransparent tubercles. The posterior outer margin of the right 

 shell (iig. 2) is armed with two spine-like tubercles, both being at the 

 lower angle near one another and of approximately the same siz(\ 

 The European form of this species seems to be larger, and the two 

 posterior spine-like tubercles vary in size. 



Seen from above the shell is broadly egg-shaped, widest just back 

 of the middle, narrowed anteriorly and bluntly rounded posteriorly. 

 The spines of the first maxillary process are toothed. The natatory 

 sette of the second antenme (tig. 8) reach about to the tips of the ter- 

 minal claws and are plumose. 



The terminal segment of the lirst foot is armed with a long, strong 

 claw and two sette, the outer one of which is not more than one-half 

 the length of the inner, which is about one-third the length of the 

 claw. Third and foui'th segments of the first foot fused, so that the 

 foot is four-segmented (tig. 4). 



The claw on the terminal segment of the second foot (fig, 5) is very 

 weak, al^out as long as the segment, the accompanying seta very 

 slender and about three times as long as the claw. Furca nearl}^ 

 straight, twent3'-four times as long as wide, dorsal margin smooth 

 (tig. 6). Terminal claw nearly straight, faintly toothed near tip, and 

 three-fifths as long as furca; subterminal claws three-fifths as long as 

 terminal one, smooth. Terminal seta weak, twice as long as width of 

 furca. 



Dorsal seta twice as long as the terminal one, and situated one and 

 one-half times width of furca from subterminal claw. 



This species may be at once distinguished by the presence of the 

 tubercles and spines on the shell and the fusion of the third and fourth 

 segments of the first foot (fig. -f). 



This description is from specimens sent to theU. S. National Museum 

 by Mr. Bailey, from Oregon. (Date unknown to me.) 



It has not heretofore been reported from America. 



Distribution world-wide. 



7. CYPRIS PELLUCIDA Sharpe. 

 Plate LXVIII, figs. 1-5. 



CypriiiotuK peUucida Shari'e, Cont. to a knowl. of the N. Ainer. f. w. ostrac. iiicl. 

 in the Fam. Cytheridse and Cyprididse, Bull. 111. State Lab. N. Hist., IV, 

 1897, p. 434, pi. XLii, figs. 1-6. 



Average length; 1.20 mm.; height, 0.75 mm.; breadth, 0.60 mm. 

 Color a clear, uniform j^ellowish brown, with no especial marking. 



«This name would seem to be preoccupied by C. peUucida Koch. However, this 

 proves to be a synonym for Candona hicens Baird. 



