SURVEY OF MINNESOTA. 239 



spreading antennae increasing the similarit}-. The glass at once 

 dispels the illusion however. 



The eggs are larger in proportion than those of quadrkornis and 

 are loosely aggregated beneath the abdomen. The cephalothorax 

 is very large and carries the usual complement of motory appen- 

 dages. The first antennae are long — exceeding the body. The 

 second pair are specialized enough to be called antennae, and the 

 claws are, according to my observation, small though they were 

 indistinctly seen. 



The abdomen is in proportion smaller than in quadricoryiis, 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 antennae is 

 shown in the figure. The color is transparent white, except the 

 tips of the antennae 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. 



-5=- 



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 col- 

 lide 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: 



Antil(zapra Americana. Ord. Pronghorn Antelope. 2 male and 2 female. 

 Custer Expedition to the Black Hills. 1874. 



