746 GEOLOGICAL SURVEY OF THE TEERITOEIES. 



OTHER FRESH- WATER CRUSTACEA ALLIED TO ARTEMIA. 



There are certain other remarkable Crustacea found living in pools 

 which are apt to dry up late in the summer, which are allied to the 

 Artemia, and are locally abundant in the far West. This notice is 

 inserted to call the attention of travellers and collectors, as well as 

 members of the survey, to them. 



First, the shelled Crustacea, or Limnadia and JEstheria. These are 

 singular Crustacea, which are protected by a valve-like expansion of the 

 back, so that the body is inclosed by two shells, and the creature bears 

 a most remarkable likeness to the bivalves of pools and streams, (Cyclas.) 

 In Texas a species of Limnadi {L. Texana Pack.) is quite common, ac- 

 cording' to Mr. Belfrage, in Western Texas in the early spring. It occurs 

 in muddy pools made after rains, and wholly disappears with the first 

 drying of the pools. "As far as I have seen, they are only found in the 

 woody bottom-lands and always near creeks." It may also be looked 

 for in Colorado, Kansas, and Montana, and probably Arizona. 



With these bivalved Crustacea occur usually in great numbers, when 

 found at all, Artemia-like animals, the Branchipus, specimens of which 

 are most desirable to compare with the brine crustacean. But the 

 most interesting of all these phyllopod crustaceans is the Apus, an animal 

 found abundantly at times in pools in Kansas, and Texas, and Mexico, 

 and the plains of the Rocky Mountains. In collecting the Apus, large 

 numbers of the young and old are desired, preserved in strong alcohol, 

 and the exact date and locality should be inserted in the bottle, written 

 on a piece of firm paper, in pencil or ink. \ 



These animals are about an inch long; a round shield, bearing simple 

 and compound eyes, protects the front part of the body, while the hinder 

 portion is long and narrow, consisting of many segments, bearing beneath, 

 leaf-like gills. The body ends in two long feelers, much like those arising 

 from the head. They have been found by Yon Siebold to be partheno- 

 genous, i. e., the females produce young from eggs without union witk 

 the other sex. 



North America is richer than any other quarter of the globe in species, 

 though it is a remarkable fact that none are known to exist east of the 

 Mississippi River. 



