166 
placed it under the Isopoda, and pointed out various separate 
resemblances to the Idotevh the Anthuridrr, and the Tanaider , 
and also drew attention to the several superficial resemblances to 
the Amphipoda, but after doing this I left the exact position of 
the genus among the other Isopoda an open question for the time.* * * § 
When preparing the “ Critical List of the Crustacea Malacostraca 
of New Zealand,” Mr. Thompson, judging from the general appear- 
ance (he had not had an opportunity of examining specimens), was 
inclined to place the genus under the Amphipoda, an opinion with 
which I did not agree, and accordingly it was arranged that it 
should be placed between the Amphipoda and the Isopoda under 
a separate heading with the following uote : — “ The systematic 
“position of this singular Crustacean is doubtful. In general 
“appearance I was inclined to place it among the Amphipoda , but 
“ from the fact of the first five pairs of pleopoda acting as branchial 
“organs, and from the absence of any such organs attached to 
“the pereion , Mr. Chilton places it among the Isopoda.— G. M. T.”f 
Unfortunately however the separate heading was omitted by 
some error, probably on the part of the printer, and the genus 
therefore appears under the last family of the Amphipoda, viz. — 
the Platyscelidw, as though it belonged to that family. It, is no 
wonder therefore that the Rev. T. R. R. Stebbingin his notice of 
the “ Critical List ” says, in speaking of Phreatoicus — “ 1 do not 
know what are the special reasons for classing it among the 
Platyscelkhe.” He also says —“The list [i.e. our ‘ Critical List’] 
continues with — •* Suborder II. Isopoda, Tribe J . Anisopoda. 
Fam. /. Tanaidie,’ and probably the affinities of Phreatoicus will 
eventually prove to be rather with the Tanaidse than with the 
Hyperina.”J In another reference to the species Phreatoicus 
typicus Mr. Stebbing calls it “a singular well-shrimp, of a new 
genus and species, which appears to be an Isopod with some 
remarkable Amphipodan affinities. ”§ 
The fuller examination that I have now made in describing the 
new species Phreatoicus australis has convinced me that the genus 
has few affinities to the Amphipoda, though it presents several 
resemblances to them, and that these resemblances are more or 
less superficial. They are briefly (1) The body, especially in the 
pleon, is somewhat laterally compressed. (2) The pleura of the 
segments of the pleon are produced downwards so as to protect 
the pleopoda on either side. (3) The legs of the pereion consist 
of an anterior series oi four, and a posterior series of three. (4) 
The general appearance of the legs and also of the uropoda is not 
* See Trans. New Zealand Institute, XV., p. 91. 
f Transactions New Zealand Institute, XVIII., p. 151, 
X Report on the “ Challenger” Amphipoda, p. 587. 
§ Loc. cit., p. 543. 
