Mar&h—North American Species of Diaptomus. 415 
In the fifth feet of the male the spines of the first basal seg¬ 
ment are rather large. The second basal segment of the right 
foot is broader than long and much swollen on the inner side. 
The lateral hair is at the beginning of the distal third. The 
first segment of the exopodite is trapezoidal, and as broad as 
long. The second segment is stout, its length exceeding its 
breadth by about one-half. At the middle of its inner margin 
is a small spine. The lateral spine is of moderate length, nearly 
straight, and denticulate on the inner margin. It is situated 
at the distal angle of the segment. The terminal hook has the 
symmetry of the curve broken by two rather abrupt, angles; 
its inner margin is finely denticulate. The endopodite is stout 
and somewhat spindle-shaped. It is attached to the side of the 
second basal segment. It is setose at the tip, and reaches nearly 
to the middle of the second segment of the exopodite. The sec¬ 
ond basal segment of the left fifth foot is quadrate and nearly 
equal in length to the corresponding segment of the right foot. 
The lateral hair is situated well towards the distal end of the 
segment. The first segment of the exopodite is trapezoidal, the 
distal end being very narrow. The second segment consists 
of an oval base and two elongated digitiform processes. The 
basal part is setose on the inner margin. Of the terminal proc¬ 
esses, the posterior one is the longer. The anterior one is 
enlarged and denticulate at tip and is separated from the seg¬ 
ment by a distinct joint. The endopodite is one-segmented and 
nearly equal in length to the exopodite. The whole foot reaches 
to the middle of the second segment of the exopodite of the right 
foot. 
Length of female, 1.2 mm. Length of male, 1.1 mm. 
The original description was from material sent by Professor 
Birge and obtained in Jackson, Mississippi. I have since found 
it in collections made by Professor Birge in Guzman and Sli¬ 
dell, Louisiana, and Schaeht reports it from lakes in Florida. 
