24 G. 0. SABS. [No. 8. 



the upper ones being struck upwards and backwards with their 

 swimming setae exposed, the lower moving at the same time in 

 the opposite direction downwards and backwards. By these 

 movements of the two pairs of antennae the animal is propelled 

 through the water at a quite even speed and constantly turns the 

 back upwards, an inverse attitude, as in the genus NotodromaS) 

 being never assumed. Now and then the animal clings to the 

 walls of the aquary or any aquatic plants; at other times 

 it dwells at the bottom, creeping about, especially by the aid 

 of the lower antennae and the 1st pair of legs. From- time to 

 time the caudal rami are seen to be stretched out beyond the shell 

 inferiorly and to be forcibly thrown backwards, the purpose for 

 this movement being either to remove some foreign particles 

 introduced between the valves, or to push the shell away 

 from some obstacle. Very often the males are seen in ardent 

 pursuit of the females, and as they are rather more active, 

 they soon get up with the latter. The shell of the female gets 

 then firmly grasped by the male posteriorly by the aid ot 

 his prehensil palps of the 2nd pair of maxillae, whereon both 

 individuals immediately sink to the bottom effecting here the 

 copulation. 



Occurrence. — The present species was raised from mud 

 derived from 3 different localities in the neighbourhood of Rock- 

 hampton, Queensland; viz., from the Gracemere Lagoon, 7 miles 

 west of that town, from another Lagoon near Racecower — ^ 

 miles from Rockhampton, and from the Crescent Lagoon — 2 

 miles from the same town. 



Distribution. — Besides from Australia the species is also 

 recorded from Nagpur, India, where it was collected by the 

 Rev. S. Hislop and submitted to the late Dr. Baird for closer 

 and description. 



