284 ZOOLOGY. 
of concentrated salt water on railroad bridges in New En- 
gland. Artemia fertilis Verrill abounds in Great Salt Lake. 
LLELLL 
Fig. 245.—Thamnocephalus platyurus, male, natural size. side and front view. @, 
head of the female ; 5, end of the body of the female, showing the ovisac. 
They may often be seen swimming about in pairs, as in 
Fig. 248. This species has a Nauplius young like that of 
Fig. 246.—Branchinectes Coloradensis Pack. 
the brine-shrimp of Europe (Fig. 244 0). It is a signifi- 
cant fact, bearing onthe question of the origin of species, 
that, according to Schmankiewitsch, Artemia may change its 
