Nicholls — Tivo Neic P}ireafoicid.s. 
205 
The persistence of epipodites ui)on four of tlie five pleopods 
furnishes still findher evidence of the ))rimitive condition of this 
form. The i)ractical (Hinality of the two pleo])od rami would perhaps 
bear the same interpretation; a condition most nearly approaching 
this being found in A. hifipcs, P. cappnsis and H ppsimetopus. In 
other forms the endopodite shows varying degrees of development. 
A feature to which little attention has been called, but 'which, 
nevertheless, seems to be unicpie in this family, is the development of 
plumose setae upon the e]ido])odite in P. capeuffis (Barnard, 1914, 
PI. XXIV). 
In the (‘ondition of the penial filament of Eophrcatoicus there is 
furnished yet another linking characUr. AFoderately curved, as long 
as its endopodite, and set with a conspicuous tuft of terminal setae, 
it exhibits a condition intermediate between that of Amphisojnifi 
(strongly curved, kniger than the endo]>otlite and without terminal 
setae) and that of P/nvYVoiVu/.s— little curved, shorter than the endo- 
podite, and with a smaller tuft of terminal setae. 
The absence of coui)liiig hooks upon the basal joints of first 
and second pleopoda in Eophreatoicus is possibly primitive, and con- 
stitutes one distinction l)etweeii this genus and Ampltinopus, which 
alone, in this family, jiossesses such structures. What are perhaps 
comparalde structures are seen on the basal joint of the second 
pleo]>od ill Kno)iu)}f/a, and coupling hooks are somewhat widely and 
variably distributed throughout the Tsopoda. 
The expanded condition of the uroi>oda, lioth in peduncle 
and rami, of Eo}/hreatoicus, is not met with elsewhere in the Phrea- 
toicidea, and finds, jierhaps, its nearest comparison with tiie condition 
in the Syncarida, where, however, the exjiansion is notable. In 
Eophreaioicus it is obviously only an expanded condition of a styli- 
form structure. 
The practical absence of a terminal i»rojection to the telson is, 
on the other hand, a mnv point of agrei'ineiit with Amphlsopus, as 
also, with PhreaioicopHis, and indeed, the jii'ofile of this region in 
Eophrcatoicus is strikingly like that of P. ‘U'itiitainattcnsis, but is, 
perhaps, not primitive, if the terminal jn'ojection is the vestige of 
the elongate telson of a Syncaridaii-like ancestor. 
A consideration of these several points justifies, I believe, the 
separation of the more typical Phreatoicids into at least three 
genera-— of which Eojdircafoicus may be regarded as occu]>ying the 
eentrnl position* and from Avliich may be derived, on the one hand, 
AmphisoimSj and, upon the other, Piireatoicus, as exemjilified by P. 
australis. 
^Though possibly itself derived from some form nearer to P. typicns 
in general appearance. 
