Nicholls — Two New Phreatoicids. 
20.3 
not the importance of the pleon region thus Ijcing- largely 
diminished. Perhaps, too, a rounded sub-cylindrical body is better 
adapted for negotiating the interstices through whieh the 'water 
percolates, for I imagine that the animals’ habitat is rather in 
such crevices than in actual siil)terranean lakes, and their 
entrance into -wells might readily l)e through ini])erfections in 
the -walls. There can be little doubt that Phrcaioicoidcs may be 
taken at the surface for precisely the same reason as that which 
brings up Hyperoedcmims occasionally. Similarly a significance 
attaches to Chilton’s statement (1906, ]). 273) regarding the first 
finding of P. kirl'U in “places that have been -well searched, for 
Mr. Thomson and myself, ami probably many others, have made 
collections in this locality -without coming across the specimens in 
question. ’ ’ It would seem likely that this subterranean form comes 
only accidentally and rarely to the surface. Hypsimcto'intu is definitely 
recognised, as is Phrcatoicopsis, as a dweller in damp earth rather 
than in subterranean water,* the latter (piite possibly coming to the 
surface occasionally, ])erha]>s, nocturnally. It has, it may be noted, 
the more usual proportions of surface-living forms (pleou-telson 
60%), and its retention of eyes would suggest that its burrowing 
habit has been acquired coni])aratively recently. 
The mandibles in EopJircatoicus seem more complete than in 
either Amjdiisopus or Phrcatoicus, but the former, in the retention of 
the secondary dentate edge of the right mandible (even though in a 
more reduced condition) seems to approach more nearly to the con- 
dition of Eophreatoicus, In this particular, Plireatoicopsis and P. 
capeiisis are in agreement with Amphisopus. 
In the condition of the first maxilla, with numerous (,5erea) 
plumose setae on the inner lobe, we are met again Avith Avhat is, 
in all probability, a })rimitive condition,^ retained in A mpliisopiis, 
but undergoing reduction in Phreatoicus. P. typicus, hoAvever, is 
stated to have nine or ten of such setae, wliile P. austraUs has four 
or five (Chilton, 1891, p. 198, and 1891, p. 158); all other Australa- 
sian species of Pkreatoicas have but four plumose setae, Init in 
every one of these (excepting P. /y/uru.s'j there are said to l^e one oi 
two setae which are not plumose. In Hypcrocdcsipus there are four 
*It has recently been noted of another group of Isopods, that 7/a/o/!- 
iscu.s (a saltAvater form) has a damp-earth representative (//. 
slepheni) ^ Avhose burrows may, perhaps, give it access to A\atei 
percolating beneath the dry surface of tlie creek (Nicholls and 
Barnes, 1926). 
fin Anaspides (vide Geoffrey Smith, 1909, pp. 507-511) this lobe 
bears numerous plumose setae, in Paranaspides eleven are 
figured (l.c. fig. 13), in Kuonanga they are reduced to three. 
