40 G- O. Sars. 



from North America, I. Halyi Brady from Ceylon, and I. 

 longiremis G. O. Sars from Australia. In my aquaria I 

 have found 2 species of this genus, which are both identi- 

 fied here with previously described forms; but in order to 

 ascertain the correctness of the identification, I have thought 

 it right to give easily recognizable figures of both on the 

 accompanying plate. 



14. Ilyocryptus longiremis, G. O. Sars. 



(PI. VII, figs. 1-10). 



Ilyocryptus longiremis, G. 0. Sars, Additional Notes on Australian 

 Cladocera raised from dried mud. Chr. Vid. Selsk. Forh. 1888, 

 p 33, PI. 4. 



.Remarks. — A species of Ilyocryptus developed very 

 abundantly in several of my aquaria, which I am unable to 

 distinguish from the Australian form described and figured 

 in the above-mentioned paper. The only reliable difference I 

 have been able to detect, is that the Brazilian specimens 

 are all of a rather pale yellowish colour, whereas old speci- 

 mens of the Australian form were dark red. But as younger 

 specimens of the latter form were much paler in colour, no 

 stress can be laid on this character, which may depend on 

 accidental circumstances. The present species is very nearly 

 allied to the form recorded by Brady from Ceylon as I. Halyi, 

 and I should, indeed, have been much inclined to regard 

 both as identical, if it were not that both Prof. Brady and 

 subsequently Dr. Daday indicate the natatory setæ of the 

 antennæ to be uniform and of inconsiderable length. In 

 the Brazilian form some of the setæ are fully as elongated 

 as in the Australian form, permitting the animal to use the 

 antennæ as natatory organs. Indeed, the specimens in my 

 aquaria, especially the younger ones, were often seen to move 



