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ENTOMOSTRACA OF MINNESOTA. 125 
The generai form and structure closely resembles that of the Cyclopide. 
The following characters are the more important ones in distinguish- 
ing the family from the other families of the order: 
Body flattened or sub-cylindrical. Abdomen usually not much 
smaller than the thorax, from which it is not separated by a sudden 
constriction; antenne rather short, 4- to 10-jointed; mandibles strongly 
toothed, palpate; maxillz well developed, palpate; first pair of maxil- 
lipeds with strong teeth at the end, second pair usually forming a 
claw. The first pair of feet are often turned forward or prehensile; 
fifth pair one- or two jointed, serving as egg supports in the female. 
Most species live among sub-aquatic vegetation. 
THE SUB-FAMILY CANTHOCAMPTIN#, 
To which our sole genus belongs, is further distinguished from the 
other sub-families of Harpacticide by the fact that the second maxilli- 
ped has a prehensile hook. The feet of the first pair are not clawed, 
but have the inner branch elongated, and the palp of the mandible is 
one-branched. 
GENUS CANTHOCAMPTUS Westwood. 
These little animals may be secured in considerable numbers by 
gathering a Supply of water from among weeds in shallow ponds and 
permitting the debris to settle in a spot where light only touches the 
jar from one side, when the Canthocampti congregate on the exposed 
side. 
Canthocamptus is an elongated animal, with the body divided rather 
obscurely into two portions, of which the first, or anterior portion, is 
largest. This part of the body has five segments, each of which has 
at least one pair of appendages. ‘The first, consisting of the bead 
proper with one of the somites of the body or thorax, as is discovered 
by observing that a pair of legs is attached to it, is the largest seg- 
ment of the body. 
As seen from above, it is triangular and extends in front into a 
short, stout beak or snout, like the rostrum of a crayfish. Above the 
beak, in the centre of the forehead, is the eye, consisting of pigment 
and two lenses, showing that we really have to do with two eyes con- 
fluent on the median line. This is the simplest form of a compound 
eye. The same method of compounding the eyes is exhibited in a 
more complicated manner by Daphnia and other Cladocera. On either 
side of the beak springs an antenna with six to nine joints of unequal 
size. The first ‘three joints are profusely covered with hairs. The 
fourth joint is more slender than the preceding, and terminates 
ina process below, which bears besides a Jong hair a peculiar blunt 
