Birge—Notes on Cladocera. 
1029 
The descriptions of these two species are still too imperfect 
to permit differentiation. Very probably they should be as¬ 
signed to a new genus. 
2. Latona parviremis sp. nov. 
Plate LXVIII, fig. 5 ; Plate LXIX, figs. 1-3. 
The common species of Latona in northern Wisconsin and 
Michigan is not L. setifera, although that species occurs there 
not infrequently. Far more abundant is a new and very dis¬ 
tinct form of the genus which I have called L. parviremis. 
This species shows characters which serve to connect Latona 
and Latonopsis, and in the possession of one structure—the 
hepatic coeca—it is unique among the Sididae. 
Description of female: The length rarely exceeds 1.8 mm.- 
2.0 mm., though it may reach 2.5 mm., excluding the setae at 
the infero-posteal angle; the height of a mature specimen is 
about 0.6 mm. In general form and structure it closely re¬ 
sembles L. setifera but is relatively less broad and fiat. The 
appendix foliaceus on the ventral side of the head is well 
developed though shorter than in L. setifera. Many observers 
must have noticed—though I have not seen the fact recorded— 
that the organ is concave on its ventral surface and forms a 
sort of trough or scoop with bottom up (PI. LXIX, fig. 3). 
It apparently serves to direct the current of food-bringing water 
in the proper direction. A small fornix is present and also 
a thin lamina over the bases of the mandibles; the last best 
seen from above. 
The valves are granulated and otherwise unmarked. Xo 
traces have been seen of the villosity sometimes found in L. 
setifera or of the brilliant colors which that species sometimes 
shows. The valves have the form characteristic of the genus, 
though the posterior margin is not so oblique to the axis of 
the body as in L. setifera. Compare PI. LXIX, fig. 1 with 
Lilljeborg, (’00, Pl. IV, fig. 12). The ventral and posterior 
margins are closely set with long, slender, plumose setae. At 
the infero-posteal angle is a cluster, about 6 in maximum num¬ 
ber, of very long setae, often quite equalling the length of the 
