Phyllopoda of Australia. 225- 



species has been generally insufficient in numbers and often too 

 badly preserved to do justice to them. In most of the groups, 

 particularly the Conchostraca, there is considerable variability 

 of form, and it is difficult to Hnd constantly reliable features, 

 also, what is constant in one genus may be inconstant in another, 

 and throughout the whole order sexually matured species often 

 alter very considerably before reaching the true adult size ; so 

 that a considerable sum of characters must be taken into account, 

 and larger and smaller forms examined, before laying down a 

 good diagnosis. 



For material I am specially indebted to Prof. Baldwin Spencer,. 

 M.A., F.R.S., and Mr. T. S. Hall, M.A., of the Melbourne 

 University, and to the authorities of the South Australian 

 Museum ; also to several other persons duly mentioned hereafter. 

 I desire further to acknowledge my obligation to Professor 

 Spencer, in his capacity of Director of our National Museum, for 

 affording me the opportunity of consulting certain literature and^ 

 examining some foreign specimens. 



I have considered it necessary to institute two new genera, 

 viz. : Parartemia and Branchinella, and have described six new 

 species, as well as redescribed and figured several others ; while- 

 the list has been somewhat shortened by the cutting out of a few 

 apparent synonyms. 



Our present knowledge of the group, however, must not be 

 considered as exhausting tlie Australian Continent; very many 

 localities, apparently, have not been searched. It is hoped that 

 further attention will be given to them by field workers, and 

 those possessing collections. 



The nomenclature is in conformity with that of Prof. Sars, 

 except as regards the endites of the branchial legs. In these 

 appendages, for the sake of uniformity throughout the group, 

 the so called coxal lobe of the Limnadiidae is considered as the 

 first endite ; allowing by this means the normal number, which 

 is six, each to bear a constant morphological relationship- 

 throughout. 



