98 



MERISTIC VARIATION. 



[part I. 



distinctive characters of A. salina. It is difficult to speak with confidence as to the 

 species of an Artemia from the female alone, but by careful comparison I can find 

 no point of structure which differentiates any of the remainder from the females 

 found with males, and I therefore regard them as all of the same species, A. salina. 

 The waters were of many kinds, some being large salt lakes, while others were small 

 salt ponds or even pools. The specific gravities of these waters varied from 1-030 to 

 1-215, and judging from the results of the analysis of six samples, the composition of 

 the waters is also very different. The specific gravities were measured in the field 

 with a hydrometer reading to -005, and on comparing these readings with the de- 

 terminations of the Sp. G. of the samples brought home it appears that they were 

 approximately correct, and I think therefore that these rough readings are fairly 

 trustworthy. As to the composition of the waters not analyzed, nothing can be said 

 with much confidence. As the analyses shew, some of these lakes contain chiefly 

 chlorides, others chiefly sulphates, and so on. In a few (e.g. xxix) there is a great 

 quantity of sodium carbonate, so much that the water was strongly alkaline and 

 felt soapy to the hands. This can generally be recognized on the spot in various 

 ways. 



The first point raised by Sehmankewitsch's work is that of the caudal fins. 

 Among my samples I have every stage between the large fins with some twenty 

 bristles, down to the condition with no distinct fin or bristles. The following table 

 gives the results as regards the number of bristles on the caudal fins, and this 



