Chilton. — The Frcsh-icater Amphipoda of Nctv Zealand. 57 



It is closely related to the next species, P. propinquus, but differs in the 

 gnathopods, having the 2 pairs similar in size and shape and with the propod 

 oval and the palm very oblique, while the carpus in each is very short and 

 triangular. 



Phreatogammarus propinquus, Chilton. 



Phreatogammarus propinquus, Chilton in Ann. Nat. Hist., ser. 7, vol. xix, 

 pp. 388-90, pi. xi (1907). 



This species was described in 1907 from a single imperfect specimen 

 collected by Mr. Crosby Smith in a small pool near the top of Mount 

 Anglem, in Stewart Island, at a height of about 2,800 ft. above sea-level. 

 In February, 1908, I obtained a few specimens from a small stream at Rona 

 Bay, in Wellington Harbour. The place at which they were obtained is 

 only a short distance above high-water mark, but the water was quite 

 fresh, and the species was found in association with Parorchestia tenuis 

 (Dana) and other fresh- water animals. I also have had for many years a 

 mounted specimen sent me from Greymouth by Mr. R. Helms, which I had 

 not previously been able to recognise with certainty, but which I can now 

 tell from comparison with Rona Bay specimens is undoubtedly a female 

 specimen of this species. 



The species is of special interest owing to its relationship to the sub- 

 terranean species Phreatogammarus fragilis (Chilton) from the underground 

 waters of the Canterbury Plains. In describing P. propinquus I pointed 

 out that the generic characters given by Mr. Stebbing required slight modi- 

 fication in order to admit the species. In the specimen then described it 

 was impossible to say whether eyes were present or not, owing to its im- 

 perfect condition ; in the Rona Bay and Greymouth specimens, however, 

 the eyes are present and well marked, so that the character " without eyes " 

 included in Mr. Stebbing's generic diagnosis will also have to be struck 

 out, and the genus Phreatogammarus is thus shown to be still nearer to 

 Gammarus. 



The Rona Bay specimens appear to be closely similar to the Mount Anglem 

 specimens originally described, except as regards the 2nd gnathopods. In a 

 female specimen, bearing eggs, from Rona Bay, the 2nd gnathopod is some- 

 what more similar in general appearance to the 1st, having the carpus mode- 

 rately long (about two-thirds as long as the propod) and subtriangular in 

 shape. The posterior margin of the carpus bears 3 or 4 short transverse rows 

 of long setae, and there are 2 tufts of setae on the anterior margin, one tuft 

 being at the distal end of the joint ; and there is a row of aboiit 7 or 8 setae 

 on the side of the carpus along its distal border. The propod is suboblong 

 in shape ; its anterior margin bears 5 short transverse rows of long setae, 

 the last one, at the joint of the finger, being the longest, and containing the 

 most setae ; the palm is slightly oblique, and is bordered by a double row 

 of stout setae, which diminish in size towards the base of the finger, those 

 at the place where the point of the finger impinges being the largest, and 

 fairly well defining the palm ; the posterior border bears a number of long 

 setae, and other tufts of setae are situated on the sides of the joint, some of 

 the longest being arranged close to and parallel to the palm ; the finger has 

 the inner margin minutely serrate, the serrations being closely approximated. 

 The whole gnathopod is somewhat larger than the 1st gnathopod, in which 

 the carpus is considerably longer, being longer than the propod, and bears 

 a more well-marked row of setae along its distal border ; the propod is some- 

 what narrow at the base, and has the palm more transverse, but in other 



