AND OF SALINITY. 273 



the range in the number of bristles on a single fin, only 

 adult females bearing eggs in the ovisac having been 

 reckoned. Only the Specific Gravities of the various 

 waters are given, but their chemical composition varied 

 between even wider limits, and this may be responsible 

 for some of the irregularities observed: 



SP. G. BRISTLES. SP. G. BRISTLES. SP. G. BRISTLES 



As this table and also Schmankewitsch's results show, 

 there is no true differentiation between A. salina and 

 A. milhausenii, in that these extreme forms are con- 

 nected by a continuous series of naturally occurring 

 intermediate forms. As Bateson remarks, " it has 

 never been shown that there is a male A. milhausenii, 

 with distinctive sexual characters, and among the 

 Branchiopoda the various sexual characters of the 

 second antennae in the male are most strikingly dis- 

 tinctive of the several forms." 



In addition to the particular character in question, 

 Bateson found that there was a great variation in other 

 characters as well. Thus he says : " Almost each 

 locality has its own pattern of Artemia, which differs 

 from those of other localities in shades of colour, in 

 average size, or in robustness, and in the average num- 



