CEUSTACEA OF NEW ZEALAND. 185 



has not been so commonly obtained as the others ; this may perhaps be accounted for by 

 its habit of creeping instead of swimming like the Amphipods. Moniez notes the same 

 thing with regard to Asellus cavaticus, Schiodte, which is frequently found along with 

 Gammarus puteaniis, bnt has not been met with from the district of Lille nor from 

 Prague, although the latter species is found at both places ; he accounts for this by 

 stating that, owing to the habits of the animal, it would rarely be brought up by the 

 pumps [78, p. 51]. 



The occurrence of Pht^eatoicns typicus has been somewhat peculiar. Although the 

 Crustacea coming up the pump were pretty carefully watched and collected from January 

 1881, no specimen of Fhreatoicus was observed until the beginning of September 1882, 

 while in a month from that date some six or seven other s^iecimens, all females, were 

 obtained. I have not taken it again since then ; but in the year 1892 a single specimen, 

 also a female, was taken at Ashburton by Mr. Smith. This species is represented at 

 Winchester by a closely allied sj)ecies, described in this paper as Fhreatoicus assimilis, 

 and of this I have three specimens only, two males and one female. 



From Leeston the following species are so far known — Gammarus fragilis, Crangonyx 

 compactus, and Cruregens fontanus ; from Lincoln, Calliopius suhterraneus ; from Ash- 

 burton, CalliopiHS suhterraneus, Gammarus fragUis, Cruregens fontanus, and Fhreatoicus 

 typicus ; from Winchester, Calliopius suhterraneus, Gammarus fragilis, Cruregens fon- 

 tanus, and the representative species Fhreatoicus assimilis. 



IV. Detailed Descriptions of the New Zealand Subterranean Crustacea. 



ISOFODA. 

 Family PHREATOICID.E. 

 Genus Fhreatoicus, Chilton. 



(Transactions New Zealand Institute, voL xv. p. 89.) 



The folloAving are the characters that I originally assigned to this genus in 1882, when 

 I had only one species, Fhreatoicus typicus, before me. They apply, with the slight 

 limitations given below, to the three species of the genus now known, and may therefoi'e 

 still stand in the form in which they were originally put : — 



" Body long, subcylindrical, laterally compressed. Upper antenna short, lower long, 

 with flagellum. Mandible with an appendage. First pair of legs subchelate, others 

 simple ; first ybr^r pairs articulated to body at the anterior ends of their segments and 

 directed forward ; last three articulated at posterior ends of their segments and directed 

 backward. Abdomen long, of sis distinct segments, last joined to telson. Sixth pair 

 of pleopoda biramous, styliform. Telson large, subconical." 



On this description I may make the following remarks : — 



1. The lateral compression of the body is not great and is seen chiefly in the pleon, 

 where the pleura of the segments are produced downward. 



2. With regard to the legs, the first pair is subchelate in both sexes, but is larger in 

 the male than in the female, and the fourth pair in the male is slightly modified so as to 



