Birge—Notes on Cladocera. 
1045 
Species. 
1. Sub-quadrate in form. Ho branchial sac on first foot. 
Length 0.6-1.3 mm. W. pannonica Daday. Hungary. 
2. Oval in form. First foot with branchial sac. Length, 
female 0.8 mm.; male 0.4 mm. W. kinistinensis Birge. 
Canada. 
Wlassicsia, like all genera of the Macrothricidae, shows 
rather complicated relations to other members of the family. 
Its closest affinities are with Grimaldina and Bunops, and in 
some ways it represents the simpler form from which these 
genera depart. Grimaldina has developed the enormous post¬ 
abdomen, while Bunops is much compressed and has a large 
dorsal crest. Apart from general resemblances, the agreement 
is particularly close in the structure of the labrum and the 
feet, in which respects the three genera agree more closely 
with each other than any of them agree with any other genus. 
5. Odontalona, a new genus of Chydorina. 
General form that of Alona. Post-abdomen long, slender; 
with numerous marginal denticles, ending in a group of very 
large denticles at angle of post-abdomen. Lateral fascicles 
present. Terminal claw with one large basal spine, attached 
some way distal to base of claw. 
This genus (which is possibly rather a sub-genus) is pro¬ 
posed for two species, Alona tenuicaudis Sars, and for an¬ 
other species first found by Daday in material from Paraguay 
and which he assigned (erroneously, as I believe) to Sars ? 
species. The name is based on the large denticles of the post- 
abdomen. 
0. longicaudis sp. nov. 
PI. LXXI, figs. 3, 4, 7. 
The form is on the whole that of Alona, though recalling 
also that of Euryalona. The head is not noticeably small, the 
rostrum reaching nearly to the ventral margin of the valves. 
