are loosely aggregated beneath the abdomen The cephalothorax is very large and carries the usual complement of motory appendages. The first antennæ are long-exceeding the body. The second pair are specialized enough to be called antennæ, and the claws are, according to my observation, small though they were indistinctly seen.

The abdomen is in proportion smaller than in quadricornis, and the tail similar to that of a young of that species. Of internal structure little was made out, but the red glands are as prominent as in the other. A curious case of malformation of antennæ is shown in the figure. The color is transparent white, except the tips of the antennæ and the last segments of the abdomen.

The process of cephalization is well illustrated by the cyclops, though not as aptly as in the larger crustaceans, the Sand Fleas.

Fig. 2,

A recent observation of a number of diatoms dipped from the bottom of the deeper portion of Lake Calhoun, seems to prove that one species is clothed with cilia throughout, and not simply at the ends as usually described. While watching the motions of a Navicula-like plant propelling itself slowly along it was seen to collide with a large mass of vegetable matter, and while thus brought to a stand-still the infinitesimal particles floating near it were seen to traverse its whole length, the diatom and particles beyond reach of its influence remaining motionless in the meantime. This specimen was of sufficient length to preclude the possibility of the cilia at the ends having any influence upon the particles.

Other Collections.

Besides the Moose mentioned in the report of last year, the fol lowing mounted mammals are on exhibition:

Antilæapra Americana. Ord. Pronghorn Antelope. 2 male and 2 female. Custer Expedition to the Black Hills.

1874.

American Elk. Custer Expedition to the Black

Badger. Custer Expedition to the Black Hills. 1874.

Ursus horribilis. Ord. Grizzly Bear, female. Custer Expedition to the Black Hills. 1874.

Corvus lencurus. Doug. White-Tailed Deer; 1 male, 2 females. Cus. Ex. Blk. Hills. 1874.

Rangifer Caribou. And. and Bach. Woodland Caribou (unmounted.) Presented Dec., 1875, by Nathan Butler.

Seiurus hudsonius. Pall. Red Squirrel. Three specimens.

Tamius striatus. Bd. Chipmunk.

Spermophilus tridecemlineatus. Mitch. Striped Gopher.

Hesperomys michiganensis. Wag. Michigan Mouse.

Procyon lotoi. Ston. Common Raccoon.

Reptiles.

Pana catesbiana. Shaw. Bull Frog.

Amblystoma tigrinum. Bd. (Immature.) Common Salamander.

Eutaenia radix. Bd. & Gir. Garter snake.

Skeletons Mounted.

Podilymbus podiceps. Lawr. Pied-billed Grebe.

Botaurus mugitans. Bart. Bittern.