TETRADE0AP0D8. 



285 



form, the change being induced by the greater or less saltness 

 of the water. Artemia produces young by budding (parthe- 

 nogenesis) as well as from eggs. ' c a b 

 A species observed near Odessa \,^ 

 produced females alone in warm 

 weather; and only in water of ^TZ; 

 medium strength were males 

 produced. The eggs of Arte- 

 mia fertilis have been sent in 

 moist mud from Utah to Mu- 

 nich, Germany, and specimens 

 raised from the eggs by Siebold, 

 proving the great vitality of the 

 eggs of these Phyllopods, a fact 

 paralleled by the similar vitality 

 of the eggs of the king-crab. 

 Fig. 344 b represents the Nau- 

 plius of the European brine- 

 shrimp. 



Order 4. — Edriophthalma. — 

 To this order belong the sow- 

 bugs (Isopoda) and the beach- 

 fleas (Amphipoda). In these ,Si.,Tnirr|S^-.!S?nt4S 



Crustacea there is no Cephalo- second antenna or clasper; «, stalked 

 ,, 1 , 1 n 1 • ,, eye ; (i, e, jaws ; /, a foot ; gr, egg-eac. 



thorax, but the head is small, —After verrui. 

 bearing two pairs of antennse, and a pair of jaws, and three 

 pairs of maxillEe. The thorax is continuous with the abdo- 

 men. Eespiration is performed by lamellate or leaf-like 

 gills on the middle feet in the Amphipods, or on the hinder 



abdominal feet in 

 the Isopods. The 

 lowest Isopods are 

 parasitic, they 

 *' graduate into the 

 Amphipods, and 

 the higher Amphipods are connected with the shrimps (Be- 

 capoda) through a group (probably a suborder) of synthetic 

 forms (Palceocaris, Acanthotelson and Oampsonyx, Fig. 

 249) such as are found in the coal formation of Illinois 



Pig. ZiS.— Artemia fertilis from 

 egg-sac ; c, male claspers. 



Great Salt Lake. 



