1036 Wisconsin Academy of Sciences, Arts, and Letters. 
that, like L. serricauda, the antenna shows distinct traces of 
a lateral lobe on the basal joint of the 2-jointed ramus, ap¬ 
proaching Latona in this detail of structure. 
The shell gland has never been described and I give a figure 
of it (PL LXVIII, fig. 3). It has the usual three loops, hut 
the posterior loop shows no trace of the great elongation so char¬ 
acteristic for L. australis and related species. On the contrary, 
the posterior loop is small, much crowded, and does not in the 
least recall that of the earlier described species. The shell 
gland of Pseudosida resembles a starting point for that of 
L. australis more than does that of L. fasciculata. The rela¬ 
tionship between Pseudosida and Latonopsis thus appears to 
be close and intricate, L. fasciculata approaching Pseudosida in 
the structure of postabdomen and first foot of male; while L. 
australis has a shell gland which looks like an extreme develop¬ 
ment of that of Pseudosida. 
The male shows no very extraordinary characters. The an- 
tennule (PI. LXVIII, fig. 2) has the regular form, long, curved, 
with a row of fine spinules on the distal part of the flagellum. 
There is no appendix ciliata or similar projection on the base. 
The whole structure is proportionally smaller than in Pseudo¬ 
sida. The copulatory organs (fig. 10) are simple, cylindri¬ 
cal, as in L. occidentalis. The first leg has a very interest¬ 
ing structure and for comparison I give a figure of the 
foot of L. occidentalis as well as L. fasciculata (figs. 6, 7, 
11). Their general form is similar, differing chiefly in the 
number and relative length of the long, plumose setae of the 
expodite. The claspers, in general alike, show noteworthy 
differences in detail. In L. occidentalis the slender process 
of the endopodite is bent at the tip into a movable claw which 
shuts against the stem. In L. fasciculata the basal part of 
the process, against which the claw shuts, is swollen and cov¬ 
ered with fine hairs. The whole structure, therefore, shows 
the beginning of a form of clasper which could easily be con¬ 
verted into the complex structure of Pseudosida. In both 
species there is present alongside of the clasper the tapering 
sensory process of the endopodite. 
The species of Latonopsis divide into two groups. One sec- 
