ENTOMOSTRACA OF MINNESOTA. 69 
of the outer ramus with its terminal claw is two thirds as long again 
as the preceding segment, the breadth of the latter two-thirds its 
length, The third joint is indicated by a single long, stout seta and 
one or two smaller ones. . 
‘*Tn the male the geniculate antenna is relatively rather slender, its 
last two joints without special appendages, its penultimate with a 
slender transparent apical process, reaching about to the middle 
of the succeeding segment, acute at tip, but neither serrate nor 
emarginate. Fifth pair of legs in the male usually without internal 
ramus to the right leg, but this ramus sometimes represented by a 
small rudiment. The limb is usually slender and its terminal claw 
short. The basal segment of the outer ramus is nearly as long as the 
adjacent segment of the pedicel, and the slender second segment of 
this ramus is fully as long. Long lateral spines borne near the tip of 
this segment. The terminal claw is about two-thirds as long as the 
segment, is somewhat abruptly angulated near its base and slightly 
recurved at the tip. The inner ramus of the left leg is very stout and 
long, reaching almost to the tip of the outer ramus, is slightly curved 
outwards, and has the apex minutely hairy. The basal segment of 
the outer ramus is thick, two-thirds as broad as long, somewhat 
inflated within, where it extends downwards beyond the articulation 
with the second segment as a rounded expansion covered with ex- 
tremely fine hairs. Second segment of this ramus longer than first, 
but only half as wide, bearing at its tip, within, a rather small, 
obliquely projecting cushion covered with cilia, and two stout terminal 
spines, one short, blunt, straight, and smooth, the other curved and 
plumose, its length about half of the segment to which it is attached.’’ 
Length 2.5 mm. 
* Diaptomus siciloides Lilljeborg. 
PLATE VIII, Fie. 10. 
De Guerne and Richard ’89. 
This species approaches D. sicilis Forbes and D. caroli Herrick very 
closely, and is said also to resemble D. gracilis Sars. From caroli it 
may be at once distinguished by reason of the fact that the third joint 
of the outer ramus of the fifth foot of the female is obsolescent. From 
the smaller form of D. sicilis it is scarcely possible to distinguish it. 
The spinous armature of the thorax and abdomen seems more 
marked, and the second segment of the abdomen is shorter in sici- 
loides and there is an appendage to the inner aspect of the basal joint 
of the outer ramus of the right leg. Last two segments of thorax con- 
fluent, bearing two lateral spines. First abdominal segment longer 
than the rest of the abdomen, laterally spined. Second segment very 
Short. Caudal stylets once anda half as long as broad. Antenne 
Somewhat exceeding the stylets. The antepenult joint of the right 
