166 



placed it under the Isopoda, and pointed out various separate 

 resemblances to the Idoteido', the AiifJmrida', and the Tanaidcp, 

 and also drew attention to the several superticial resemblances to 

 the Aniphipoda, 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 tlie 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 note: — " 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 oi pleopoda acting as branchial 

 "organs, and from the absence of any such organs attached to 

 "the pereion, Mr. Chilton places it among the hopodn. — 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 tiie last family of the Amphipoda, viz. — 

 tiie PlatyKcchdfi', as though it belonged to that family. It is no 

 wonder therefore that the Kev. T. R. R, Stebbing in his notice of 

 the " Critical List '' says, in speaking of PhrccUoicHS — " I do not 

 know what are the special reasons for classing it among the 

 Platyscelida\" He also says — "The list [i.e. our ' Critical List'] 

 continues with — ' Sahordcr II. Isopoda. Tribe I. Anisopoda. 

 Fmn. I. Tanaida^,' and probably the affinities of Phreatoic-nn will 

 eventually prove to be rather with the Tanaidte than with the 

 Hyperina."! In another reference to the species Phrentoieus 

 typicns 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 Phreatoicns ausfrnlis has convinced me that the genus 

 has few affinities to the Amphipoda, though it presents several 

 re.-teinhlartces to them, and that these resemblances ai'e 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. (.''>) The legs of the pereion consist 

 of an anterior series oi four, and a posterior series of f/iree. (4) 

 The general appearance of the legs and also of the uropoda is not 



* See Trans. New Zealand Institute, XV., p. !U. 

 t Transactions New Zealand Institute, XVIIl., p. loi. 

 X Report on the " Challenger" Amphipoda, p. 587. 

 § Loo. cit., p. 5I3. 



