304 



ZOOLOGY. 



of concentrated salt water on railroad bridges in New En- 

 gland. Artemia fertilis Verrill abounds in Great Salt Lake. 



liea 



Fig. 250. Thamnocephalus platyim/s, male, natural size, side and front view, a, 

 ?ad of the female ; b, end of the body of the female, showing the ovisac. 



They may often be seen swimming about in pairs, as in 

 Fig. 253. This species has a Nauplius young like that of 



Fig. 'HSi.Branchinectes Coloradensis Pack. 



the brine-shrimp of Europe (Fig. 249 b). It is a signifi- 

 cant fact, bearing on the question of the origin of species, 

 that, according to Schmankiewitsch, Artemia may change its 



