CRUSTACEA OF NEW ZEALAND. 209 



importance from a systematic point of view, for we have threat differences in tbis respect 

 in species of Idotea and in some of the Cymothoidte, and, on tlie whole, I think we must 

 place Phreatoicits somewhere near to the Asellida;, hut forming a separate family, the 

 Phreatoicidse, which hears to the Asellidae somewhat the same relation that the CaprelUdae 

 do to the Cyamidae in the Am2)hipoda. Limnoria may perhaps be placed, as is done by 

 many authors, in a separate family, the Limnoriidic, possessing some of the ancestral 

 characters of the Asellidir, and thus approaching nearer to the Phreatoicidae. Gerstaecker 

 puts Limnoria under the Spha;ronid;c, but forming a separate section, the Limnorina 

 [45, p. 220]. 



From what has been already said it will be seen that JPhreatoicus occupies a fairly 

 central position among the Isopoda, retaining to a greater extent than any others the 

 typical characters of the Isopoda. 



The following are the characters which I have provisionally advanced for the new 

 family Phreatoicidfe. These are simply givt-n for the sake of comparison, and will no 

 doubt require revision when other forms allied to IPhreatolcus are discovered : — 



Familv PHREATOICID.E. 



"Body subcylindrical, more or less laterally compressed. Mandil;)les with a well- 

 developed appendage. Legs distinctly divided into an anterior series of four and a 

 i:)Osterior series of three. Pleopoda broad and foliaceous and branchial in function, but 

 not protected by an operculum. Pleon * large, of six distinct segments. Uropoda 

 styUform." [26, p. 151.] 



Pamily ANTHURID^. 



Genus Cruregexs, Chilton. 

 (Transactions New Zealand Institute, vol. xiv. p. 175.) 



The following characters were assigned to this genus when I originally described it : — 

 " Body subcylindrical. Head small. First six thoracic segments subequal, the seventh 

 small and icithout appendages. Antennae subequal, neither having a flagcllum. First 

 pair of thoracic legs large and subchelate, the second and third subchelate but smaller ; 

 the three posterior pairs simple. First jiair of abdominal appendages forming an 

 operculum enclosing the branchial plates, last pair biramous. Telson squamiform." 



It is scarcely necessary to explain that the above description was drawn up by a tyro 

 in the study of the Crustacea, and that though modelled on the descriptions given bv 

 others of allied genera, it contains much that is tmnecessary and little that is essential. 



The genus appears to fall under Norman and Stebbing's [100] " Section B," though 

 the mouth-parts are even more modified than in the species assigned to this section by 

 these authors. The following generic diagnosis may be given for the sake of comparison 



* I have substituted " pleon " for " abdomen," which I had inadvertently put in my original diagnosis. 



