1885.] 



CLADOCERA. 



35 



to the water. The number of individuals had now become far 

 too great in proportion to the size of the aquary, and from this 

 cause apparently, after some days a sudden mortality ensued, 

 occasioning all of the animals to disappear in comparatively a 

 very short time. Previous to this occurrence, I had fortunately 

 submitted to examination some of the females in which ephippia 

 were developing, as also a few individuals of the diminutive male 

 observed at that time, and thus I could trace with comparative 

 completness the lif-history of the present form. 



As is well known, the Northern species of Moina are, as a 

 rule, met with in very small turbid ditches, generally appearing 

 only at certain seasons of the year (in our country mostly in 

 the latter half of summer), whereas no species of this genus has 

 ever been found in lakes of any extent. Thus, it may seem 

 somewhat strange to lind this form among the Cladocera derived 

 from one of the larger Australian lakes. We must however bear 

 in mind, that the lake in question is very shallow, and that some 

 years ago it even completely dried up, having thus, apparently 

 at least for some time, presented conditions eminently favou- 

 rable to the existence of the present form. 



Family: — Lynceidæ. 

 5. Leydigia australis, n. sp. 



(PL 7, 8). 



Specific Character. — Female: — General habitus very 

 similar to that of L. acanthocercoides. Head comparatively 

 erect, with rostral projection curved but very little, if at all 

 at apex. Carapace without any distinct sculpture, compressed, 

 broadly quadrangular, dilated behind and very obliquely truncate, 

 with upper angle obtuse, lower corner projecting and rounded off. 

 Eye very small. Ocular spot enormously developed, at least three, 

 times the size of the eye, and irregular-angulous in form. An- 

 tennulæ reaching scarcely to apex of rostrum. Inferior expansion 

 of labrum delicately ciliate at edge. Tail with 3 bunches of hairs 



3* 



