CEUSTACEA OF NEW ZEALAND. 217 



these setae appear to be simple, but among them are two small groups, each containing 

 two " auditory setae." The cxpotlite is articulated to the dorsal and outer surface of the 

 peduncle near its anterior end : it is slender, and consists of a thin rod or narrow plate, 

 a little deeper than broad, and shows no tendency to enclose the hinder end of the pleon 

 as in Anthura, &g. ; it reaches slightly beyond the extremity of the peduncle, and has 

 its upper and lower margins and the extremity fringed with setae, those at the end being 

 the longest. 



The telson (see fig. 20) is slightly longer than all the preceding part of the pleon ; 

 it is squamiform, rather more than half as broad as long, the distal portion ovate, the 

 extremity tipped with five or six small setae. 



The telson is distinctly separated from the sixth segment of the pleon, a very unusual 

 feature in the Isopoda, which generally have the sixth segment of the pleon and the 

 telson confluent ; this character is, in fact, so constant that it is given by Blanc [12] as 

 one of the points of difference between the Isopoda and the Amphipoda. Most authors 

 have drawn the telson of Anthura and other species as separate from the sixth 

 segment of the pleon, but I am not aware that anyone has drawn special attention to 

 this unusual character. 



It will be seen that I have described the uropoda as consisting of a peduncle and two 

 branches, each consisting of a single joint, whilst most authors have described the inner 

 branch as ^zco-jointed, considering the part I have taken as the flagellum to be the first 

 joint of the endopodite. If the endopodite were really two-jointed it would be an excep- 

 tion from all other Isopods. It may consist of several joints in the Tanaidae and the Apseu- 

 didse, which differ in several well-marked features from the Isopods, but in all others, so 

 far as my knowledge goes, the endopodite never consists of more than a single joint. 

 The interpretation of the uropod that I have given is certainly correct for Cruregens, for 

 in this genus the exopodite can be plainly seen to be articulated to the dorsal side of the 

 peduncle, and the peduncle is quite continuous past the base of the exopodite to its 

 junction with the sixth segment of the pleon ; this can be seen both above and still 

 more easily below. In most other species of the Authuridae the exopodite is broad and 

 its articulation extends right across the peduncle, thus concealing its true nature. 

 Gerstaecker [45, pi. xiv. fig. 26] certainly figures the uropod of Paranthura costana, Sp. 

 Bate, with a short separate peduncle bearing two branches, one of which is ^tco-jointed ; 

 but his figure is not very clear, and I think he has probably been misled in the way 

 suggested above. Dohrn [36], dealing with the same species, interprets the uropod in 

 the same way that I have done, and as I had formed my own conclusion before con- 

 sulting Dohrn's paper, I was particularly pleased to find my opinion confirmed bv him. 

 This portion of his paper appears to have been overlooked by systematic writers on the 

 Anthuridac. The great enlargement and elongation of the peduncle in Cruregens, 

 Anthuriajjic., are only exaggerations of what we find in most of the Oniscidae, where 

 the two rami are widely separated ; and in Hyssura, Norman and Stebbing [106, pp. 128, 

 129, pi. XXV. fig. v.), we have evidently an intermediate form where the peduncle is 

 quite short and the two rami therefore much more closely approximated at their bases. 

 Even in this genus, however, Stebbing and Norman speak of the endopodite as two- 



