198 Nicholls — Two New Phreatoicids. 
movement, swimming rajjidly with a <]uick, scurrying motion 
(effected apparently largely, if not entirely, by the uropods), re- 
markably like the jerky movement of an Amphipod. Indeed, a small 
specimen may readily bt‘ mistaken, in its sidewise motion, for an 
Amphi])od. Like an Amphipod, too, it may swim in the erect 
position, this, by the movement of the pleopods. The larger 
Western Australian form is, perhaps, slightly less agile. 
Glauert notes of A. ixduatris (19-4, ]}. 49): — ‘ ' Tlie animals arc 
fairly active and exceedingly (piick at burrowing into the soft 
nunldy bottom .... when not burrowing (they) prefer dark or 
shady corners. Their food seems to consist of animal and vegetable 
matter, and they make most effective scavengers.” 1 have offered 
small ]>o]’tioJis of dead earthworms, insect larvae, etc., l)ut have never 
observed that this material has been touched. The preference for 
dark s])ots is particularly noticeable in the females, and, in rounding 
up my specimens, those are })ractica11y always the last to be secured. 
Pairing seems to extend ovei’ a comparatively long period, 
couples taken together have so continued for fifteen days subse- 
quently, the brood pouch enlarging visibly during that period. In 
a small female of about 11mm. the brood were discharged on the 
twenty-eighth day after the separation of the pair, no fcAver than 
fifty-one young issuing at that time. The male of this pair under- 
went eedysis a couple of days prior to the emergence of the young, 
but the female had not shed her skin four weeks later when she was 
again pairing. 
The process of eedysis must have a considerable importance to 
these animals, even when full size is attained, if they are living 
in a comparatively small water hole, for, under such conditions, 
they become tliickly covered with encrusting organisms, even to the 
plumose hairs of the ])leopods. In A, p(dustris a small Vorticellid is 
very common and o(‘casionally a Bendroconietes-like form may be 
found, best seen on the cast skin and n])]tarently most affecting tlie 
antennae and the gnatho[)ods. Barnard notes a similar infestation 
in }\ capcii.sis by ‘‘a short-stalked Infusorian,” while (diilton, also, 
remarks upon the heavily infested condition of P. austroJis. The 
dense covering of Kotifers, etc., in P. Joyneri has been mentioned 
above. That the instinct for concealment is apparently inore 
strongly develo])ed in the female is probably the explanation of the 
fact that collections usually contain a large preponderance of males 
unless the collecting has been acconi])lished by an indiscriminating 
use of the scooj) or net in the muddy or weed-grown hiding ])laces. 
Thus Chilton (1891, 16o) notes of his material of P. australis, 
•Aiearly two-thirds were undoubtedly males.” In the collection of 
Eophrcatoiciis which I have examined at least three-quarters were 
