438 Wisconsin Academy \of Sciences, Arts 3 and Letters. 
extensive collections have been made in that state, hut it would 
seem probable that it must occur in many localities between 
the Mississippi valley and the sea-board. 
In the description, as given above, the original description 
is modified by the more complete knowledge made possible by 
the study of a larger number of individuals. 
diaptomus siciloides Lilljeborg. 
Plate XVIII, fig. 9. Plate XIX, figs. 4, 5, 7. 
1889. Diaptomus siciloides Lilly, DeGuerne and Richard, p. 
54; pi. I, figs. 7, 8, 28, 32. 
1895. Diaptomus siciloides Herrick and Turner, p. 69; pi. 
VIII, fig. 10. 
1897. Diaptomus siciloides Schacht, p. 154. 
1898. Diaptomus siciloides Brewer, p. 125. 
1905. Diaptomus siciloides Pearse, p. 147; pi. XIII, fig. 5; 
pi. XIV, figs. 7, 8. 
A small species. The first segment of the cephalothorax 
about equals in length the three succeeding segments. The 
last segment terminates in two lateral spines. 
The first abdominal segment of the female a little exceeds 
in length the rest of the abdomen. It is expanded laterally 
and in front, and bears two small lateral spines. The second 
segment is considerably shorter than the third, and the third 
and the fureal rami are about equal. The fureal rami are 
ciliate on the inner margin. 
The antennae are 25-jointed and reach the extremity of 
the furcal rami. The right male antenna is much swollen 
anterior to the geniculating joint. The antepenultimate seg¬ 
ment bears a hook which equals in length one-half of the pe¬ 
nultimate segment. 
The first basal segments of the female fifth feet are armed 
with the customary spines, and the second basal segments with 
the usual lateral hairs. The exopodite is composed of two 
segments, the third segment being represented by two spines. 
