CRUSTACEA OF NEW ZEALAND. 245 



pleopoda are specialh' modified, the penial filament being formed from a portion of the 

 endopodite, a fact that will perhaps be useful to throw light on the more modified 

 second pleopoda in the males of various Asellidse, &c. 



(3) A consideration of the eoxoe of Phreatoicns leads to a short discussion in support 

 of Spence Bate's contention that the "epimera " or " side-plates " are in reality the coxa' 

 of the appendages of the perseon. 



(4) In discussing the systematic position of Phreotoicus reference is made to the 

 external characters by which the Amphipoda are separated from the Isopoda, and an 

 additional difl"ei'ence is shown to exist in the ischia of the appendages of the perteon, as 

 these are of moderate length in all Isopoda except the Apseudidai and Tanaidse, whih' 

 they are almost always very short in the Amphipoda. 



(5) The genus Critregeifs, belonging to the Anthuridse, is described and compared 

 with some allied genera. It has only six pairs of legs, and thus appears to perma- 

 nently retain this larval character of the Isopoda, owing probably to an arrest of 

 development. 



(6) The mouth-parts of Cruregens, which are very diificult to determine, are fully 

 described, and it is shown that the mandibles are small and without any trace of a 

 palp — a character very exceptional in the Anthuridae. 



(7) The terminal uropoda of Cruregens are shown to consist of an oblong peduncle, 

 a long narrow exopodite arising from near the anterior end of the peduncle, and a 

 one-jointed endopodite arising from its posterior end. Other authors, with the exception 

 of Dohrn, have apparently wrongly described the uropoda of the Anthuridoe as having 

 a two-jointed endopodite, the distal portion of the pedvmcle having been mistaken for a 

 part of the endopodite. 



(8) The telson of Cruregens and of some other Anthurids is distinctly separated from 

 the last segment of the pleon, though this is exceptional among the Isopoda. 



(9) The genus Crungomjx is discussed at some length, and the mouth-parts of 

 Crangonyx compactus are described. The mouth-parts of Crangonyx do not appear to 

 have been previously described. 



(10) The pleopoda of Crangonyx compactus have each only one ramus instead of two, 

 as is almost universally the case in other Amphipoda. It appears to be the inner branch 

 that is wanting. Nothing appears to be known of tlie pleopoda of most of the other 

 species of Crangonyx. 



(11) The species Gammarus fragilis appears to correspond well with the characters 

 usually assigned to tlie genus, but it is interesting to note tliat the present species has 

 very long antennae, perieopoda, and terminal uropoda, thus showing some approach to 

 the characters of Nlphurgus. 



32* 



