1888.] 



AUSTRALIAN CLADOCERA. 



hook on the first pair of legs, as also by the very different form 

 of the tail. In the latter respect it is also very markedly dis- 

 tinguished from the male of A. Archeri, described above. 



The antennulse, on the other hand, do not materially differ 

 from those organs in the female, since they are not very much 

 larger and scarcely projecting beyond the tip of the rostrum. 



The tail (fig. 10), as stated above, looks very different from 

 that in the female. It is considerably narrower, almost conical 

 in form, and tapers gradually to an obtuse point. The dorsal 

 edge is in its upper part somewhat irregularly arched, but does 

 not exhibit any distinct supraanal angle; nor is there any trace 

 of denticles to be seen on the outer part of the dorsal edge. 

 The caudal claws are very small and without the slightest trace 

 of the basal secondary denticle; moreover their place seems 

 rather anomalous, being inserted just behind the obtuse extremity 

 of the tail, close to its dorsal edge. 



The testes exhibit a structure very similar to that described 

 above in the male of A. ArcJieri, and have, as in that species, 

 their outlet at the tip of the tail, in front of the caudal claws. 



The colour of the male is about the same as that of the 

 female, with this difference, however, that the whole tail has 

 a dark brownish tinge. 



Observations. — I first observed this species in the begin- 

 ning of September 1886, on returning from an excursion. They 

 were present in only one of my aquaries, prepared on the 9th 

 June same year, but in great profusion, both males and females, 

 the latter for the greater part with winter-eggs. In its habits this 

 species does not in any way differ from the two preceding ones. 



Occurrence. — The mud that yielded that species was taken 

 according to the label on the 14th March 1885, from the Crescent 

 Lagoon — 2 miles from Rockhampton, the same locality whence 

 several other interesting Entomostraca were raised, among others 

 the above-described species of Macrothix. 



6 



