284 THE AMERICAN MONTHLY [December, 



Mr. VVray, of Highgate, has recently made, by request, for a 

 friend of mine, a "• 5-inch " (true 4^-inch) of superb quality for 

 a " triplet " or " single-system " glass. With E ocular it pre- 

 serves perfect definition, and gives the spirals of trachea and simi- 

 lar details w^ith full sharpness and absence of color dispersion. 

 Were there any demand, I have no doubt that makers could pro- 

 <luce a true 5-inch objective (which they would probably call '^ 6- 

 inch ") of equal merit. — English Mechanic^ Nov. 18^ l8g2. 



The Brine Shrimp of the Oreat Salt Lake. 



By J. E. TALMAGE, Ph. D., F. R. M. S., 



SALT LAKE CITY, UTAH. 



The brine ^irimp, Artc7nia fe7-tilis (Verril), is a tiny crus- 

 tacean abounding in the water of the Great Salt Lake. They fre- 

 quent the surface ; indeed I have never taken a specimen from a 

 depth beyond two feet. They may be foimd in the lake at all 

 seasons, though they are most numerous between May and Octo- 

 ber. I have taken them in the midst of winter, when the temper- 

 ature of the water was far below the freezing point; it will be 

 remembered that the concentrated brine of the Lake never freezes. 

 The females greatly preponderate ; in fact, during the colder 

 months it is almost imjDossible to find a male. In the latter part 

 of summer the females are laden with eggs, from four to sixteen 

 having been repeatedly counted in the e^^^ pouch. The males 

 are readily recognized by the very large claspers upon the head. 



The artemice frequent the shores during calm weather, but 

 rain drives them into the lake. Oftentimes they congregate in 

 such numbers as to tint the water over wide areas. Thev are 

 capable of adapting themselves to great variation in the composi- 

 tion of the water, as must necessarily be the case with any inhab- 

 itant of the Salt Lake, for that body of water is subject to wide 

 fluctuations in bulk and composition. Aside from the long 

 periods of rising and falling of the waters, there are great annual 

 variations caused by the relative supply of w^ater through rain and 

 snow-fall and the loss by evaporation. Beside the annual fluctu- 

 iition, the lake is at present steadily falling, and the waters are 

 consequently growing more concentrated. I have specimens of 

 artemia gathered from the lake in September, 1892, and the water 

 taken then showed on analysis 14.623.23 grains of dissolved solids 

 to the imperial gallon, the greater part of this being salt. Indeed 

 I have captured the creatures in the evaporating ponds of the salt 

 works, where the brine was near its point of saturation. It is not 

 difficult to accustom them to a diluted medium ; I have kept them 

 alive for days in lake water diluted with 25, 50, 80, and 90 per 

 cent, fresh water, and from eight to eighteen hours in fresh water 

 only. Of course the changes from brine to fresh water were made 

 gradually. 



