minute structure, in the number of joints of the antennæ and from Penilia, in having the first joint of the longer ramus shorter than the second.

The branch which is three-jointed in Sida is not the one which has the short terminal joint.

Daphnella Winchelli. Herrick.

This species closely resembles D. Wingii, Baird, but I have no hesitation in pronouncing it distinct. Length .03 in. Head rather short. Carapace pearshaped, transparent. Superior antennæ short, but appearing on either side the head when the animal is swimming, they appear to have three setæ at the extremity. Inferior antennæ very long, as long as body. The shorter ramus has four setæ on the terminal joint and one on the first, while the other ramus carries eight on the terminal joint besides, one that is much shorter than the others, and the first joint has four.

The tail has long diverging stylets, and seems not to have the minute teeth of the D. Wingii. The posterior portion of the front of the shell-margin is ciliated or spined. The back of the head seems to have the same appendage described in Sida. Ova two. This species was found in Minnetonka creek and is named in honor of Prof. Winchell.

FAMILY POLYPHEMIDE.

Genus Polyphemus. Muller.

Bibliography.-Polyphemus, Muller, Cuvier, Latreille, Strous, etc.

Baird, Brit, Entomost. p. 111.

Dana, Wilkes' Exp. p. 1266.

Characters-Body incurved toward the head except the posterior portion of the abdomen, which projects backward and is very slender, bearing two long spines at the extremity. Head distinct. Rami of posterior antennæ three, and fourjointed.

Polyphemus occidentalis. Herrick.

Length .25 in. Body excessively incurved, as is the head. Eye large, filling the head. Superior antennæ apparently obsolete. Inferior antennæ small. Jaws two or three-jointed, three-toothed at the apex. Feet, four pairs, first pair long, apparently four-jointed and three-clawed at the end, basal portion ciliated on the posterior margin. Fourth pair of feet nearly rudimentary. The abdomen is very long. Found in "Mud Lake," south of Minneapolis.

Eurycercus lamellatus. Muller?

Several specimens belonging to Baird's genus Eurycercus were found, and as far as can be determined they are not specifically distinct from E. lemellatus, though they are less in size and have a few minor points of difference.

I append his description, omitting the bibliography:

"Shell of an olive color; rather square-shaped, ciliated on anterior margin; ventricose in centre, and arched on posterior edge. Beak rather blunt and short, superior antennæ stout, somewhat conical, slightly curved and terminating in

The posterior branch has
Abdomen very wide and

six spines, each of which gives out a fine seta. Inferior antennæ short compared with the size of the insect. Anterior branch has five long filaments, three from the terminal, and one from each of the other joints. short spines on the two basal joints. Eye large. densely ciliated. This is the largest member of the family, its motion is a succession of bounds. This animal is heavy and slothful compared to other species.

PLATE I.

Diaptomus longicornis, Herrick.-Back view of the female and side view of the male. a, basal portion of male antennæ showing geniculating joint.