TETRADECAPODS. 



305 



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

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

 nogenesis) as well as from eggs. c ad 



A species observed near Odessa V 



produced females alone in warm 

 weather; and only in water of 'l~2'.Z. 

 medium strength were males 

 produced. The eggs of Arte- 

 inia fertilis have been sent iu 

 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. 249 b represents the Nau- 

 plius of the European brine- 

 shrimp. 



Order 4. — Tetradecapoda. — 

 To this order belong the sow- 

 bugs {lao-podd) and the beach- 

 fleas (Avijjhijwda). In these 

 Crustacea there is no cephalo- 

 thorax, but the head is small, 

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

 pairs of maxillffi. 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 

 S^o^S^^S^^^^^'^^^^S^. the Isopods. The 

 lowest Isopods are 

 parasitic, they 

 graduate into the 

 Amphipods, and 

 the higher Amphipods are connected with the shrimps (De- 

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

 forms {PalcBOcaris, Acanthotelson and Gampsonyx, Pig. 

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



Fi^. 252.— Brine- shrimp, Arlemia 

 gracilis, enlarged, a, first anteuna ; 6, 

 second antenna or clasper ; c, stalked 

 eye ; d, e, jaws ; /, a foot ; g, egg-sae. 

 —After Verrill. 



Fig. iWi.— Artemia fertilis from Great Salt Lake, 

 egg-sac ; c, male claspers. 



