CEUSTACEA OF NEW ZEALAND. 235 



of peracopoda long and slender, each much longer tlian the preceding. Second uropods 

 with the outer branch only about half as long as the inner. Tclson rather short, sub- 

 rectangular ; posterior angles rounded and each furnished with a single fine seta; hinder 

 margin slightly concave. 



Female. Differs from the male in the following points : the size is smaller, only about 

 two-thirds as large ; the antennae are more slender and less strongly supplied with setaj, 

 and apparently do not bear calceoli ; the gnathopoda are much smaller and more slender, 

 the first having the carpus triangular, as long as thepropodos, which is elliptical, and has 

 the palm only slightly oblique ; the second gnathopod is very long and slendei*, carpus 

 and propodos similar, narrow oblong, carpus much longer than propodos, palm of latter 

 quite transverse. 



Length. Largest male 12 mm. ; largest female about 6 mm. 

 Colour. White, semitransparent. 

 ^*^ Habitat. Eyreton {Chilton), Lincoln {E. Wilkinson), Ashburton {W. W. Smith and 

 J. B. Mayne), Winchester {D. L. Inwood) : in wells. 



Remarks. The female of this species bears a very close general resemblance to Pherusa 

 ccei'ulea, G. M. Thomson [107, p. 2()GJ. I had judged this to be the case from the 

 comparison of Stebbing's figures of the latter with my specimens, and an examination 

 of specimens of Pherusa ccerulea, kindly supplied by Mr. Thomson, shows that the 

 resemblance is even closer than I had imagined. Pherusa ccerulea is stouter in body, 

 has the side-jjlates deeper, and of course differs also in the possession of eyes and in 

 its very distinct dark blue colour, but in the form of the antennae, the mouth-parts, and 

 the gnathopods there is little difference of any importance. The upper antenna has a 

 rudimentary secondary flagellum (not mentioned in Stebbing's description), as in Cal- 

 liopius subterranetts, but it is somewhat longer, being longer than the first joint of the 

 main flagellum ; in the specimen I have dissected there are small calceoli on both 

 antennae, just as in the specimens of Calliopius subterraneus that I have described below 

 as " immature males." The gnathopods have the same general shape, but are not so 

 long and slender, and, especially in the second, do not bear so many tufts of sette as in 

 tlie female of CalUo])ius subterraneus ; the pcraeopoda are shorter, the uropoda are similar 

 and in like manner armed Avith spines, but the second has the branches less unequal 

 in length, and the telson is rounder. The specimen of Pherusa ccerulea that I have 

 examined is probably a young male, but none of the few specimens in my hands have the 

 gnathopoda so largely developed as in Calliopitis stibterraneiis. On the whole it appears 

 that the two species are very closely related, and either Calliopius subterraneus has been 

 derived from Pherusa ccerulea, or, what is more likely, both have been derived from a 

 closely allied species once widely spread in New Zealand. 



Calliopius jluviatilis, G. M. Thomson, is very common in freshwater streams in New 

 Zealand, but is not so closely allied to the subterranean species as is Pherusa ccerulea. 

 It differs considerably in the gnathopoda, and in the last pair of pcraeopoda, which 

 have the last joint simple, ending in a small pencil of long haii-s, as in species of 

 the CEdiceroidae, and it seems scarcely necessary to compare it in detail with Calliopius 

 subterraneus. 



SECOND SERIES. — ZOOLOGY VOL. VI. ;U 



