CRUSTACEA OF NEW ZEALAND. 225 



anterior marp;in with a small tuft at the base of the dactylos aud a single seta situated 

 more proximally. The dactylos is short. 



The second perccopod is exactly similar to the first in size and form. 

 The third, fn)irtli, and fifth pera^opoda are all similar to each other, but eacli is 

 slightly larger than the preceding ; they are all somewhat remarkable in having the 

 basos rather narrow and not expanded posteriorly into a semicircular plate as in most 

 Amphipoda. Eig. 23 represents the fourtli peraeopod, and it will be convenient to 

 take this one for description, as it represents a mean between the fifth and seventh. 

 The coxa is almost semicircular, upper margin straight, the lower convex margin 

 thickly fringed with short spines, which are most numerous posteriorly. Tlie basos 

 is narrowed a little at the base ; it is oblong, the breadth being slightly more than 

 one-third the length ; anterior margin Avitli two setae, one at the extremity and one 

 above it; posterior margin straight, with two or three stout setoe about the middle 

 and one or two longer ones at the extremity. The ischium is very similar to that 

 of the preceding perseopoda ; the meros oblong, about three times as long as broad, 

 both margins bearing stout setae, especially at the extremity ; the carpus slightly 

 lons^er than tlie meros, but a little narrower, the seta? on it more numerous and lar^-er 

 than in the meros; the propodos as long as the carpus, but narrower, aj)parently 

 twisted so that the dactylos projects backwards, both margins having stout sette or spines, 

 those on the posterior margin being most numerous ; the dactylos is short, not much 

 longer than the setae at the end of the propodos. 



The pleopoda (figs. 24, 25, 26) are small and are very remarkable, in that each bears 

 only one branch, which appears to be the outer one, there being no trace whatever of 

 the second branch. I do not know of any other species of the Amphipoda where this 

 is the case : in the CempUicB the inner branches may be rudimentary and even entirely 

 absent in the case of the third pleopod ; but it is easy to see that this is due to the 

 habit of the animal living in a tube, which has to some extent modified all its 

 pleopoda aud the tail-part. In the present species the portions of the pleopoda that 

 are present appear quite perfect, and I know of nothing in the habits of the animal 

 to explain why these pleopoda should have only one branch while those of Gammarus 

 fragilis and Calliopius subterraneus have the normal two branches. 



The first pleopjod (fig. 24) is the longest ; the basal portion is oblong, slender, 

 without setae, except the two " coupling spines " at the extremity of the inner marf^in • 

 these seem not unlike those of Niphargus, each bearing two or three tubercles on the 

 one side and being slightly hooked at the end. The single branch is nearly twuce as 

 long as the peduncle and consists of eleven joints, each bearing the two long plumose 

 setae in the usual way. I cannot find any trace of the " cleft spines " mentioned by 

 Stcbbing [108, p. xiv &c.], Sars [91, p. 53J, Humbert [62, p. 351], &c., on the inner 

 margin of the first joint of this branch, and it is therefore probable that it represents the 

 outer branch, the inner one being absent. 



Stebbing [108, p. xiv] has drawn special attention to these " cleft-spines " and also 

 to the "coupling-spines," and, with regard to the latter, points out that they have been 

 described aud figured by Sars in his account of Gammarus neglectiis [91, p. 53], and 



