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AUSTRALIAN MALACOSTRACOUS CRUSTACEA. 211 
40. Alope palpalis (White).—May be found in shady nooks 
amongst the rocks at low tide, but is not at all common. It must 
also occasionally swim freely, as I have taken it from the stomach 
of the “ Jew-fish” (Sciena antarctica).. Covered with short red 
sete. Palpi very large. Port Jackson. 
Tribe SToMATOPODA. 
41. Squilla levis (Hess).—The common “ Hass-crab”’ of Port 
Jackson. Caught principally in the Prawn-nets, travelling in 
company with Peneus esculentus, on which it partly subsists. It 
may often be procured from the stomach of Sciena antarctica, of 
which fish it forms one of the principal articles of food. Coast 
of New South Wales. 
Order EpRIOPHTHALMATA. 
Sub-order Isopopa. 
ribe FLABELLIFERA. ' 
42. Ceratothoa trigonocephala (Leach).— This is the com: 
monest and best known of our fish parasites. As a rule, it 
inhabits the mouth of the “ Yellow-tail,” Trachurus declivis 
(C. & V.). The head is almost triangular, and deeply encased in 
the anterior portion of thorax. The Ceratothoa embryo is very 
different to the adult. The five segments of the pleon, which in 
the adult have coalesced, are movable upon each other. Pleon is 
nearly as long as pereion, but in the adult it is so insignificant as 
to be scarcely so long as one pereion somite. The telson too 
widens out posteriorly when the animal reaches maturity. Al- 
together the young Ceratothoa is fitted for a free existence, and 
no doubt the adult was the same at one time, but has been 
gradually adapted to living a parasitic life, thereby undergoing 
change of formation. Colour white. Port Jackson. 
43. Nerocila sp.?—This Isopod is another of the parasitic 
Crustacea, having for its host the Sea-mullet, Mugil grandis 
(Cast.). It is not so convex as the preceding species, and the 
epimera are very long. Kyes are entirely wanting. Colour some- 
times dark brown, also yellow. 
44. Cymodocea pubescens (Hasw.).—The small crustaceans of 
this name are “rock-borers.”’ The boring is done exclusively 
with the uropods, which form two strong spikes. In burrowing 
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