G. M. Thomson. — On the New Zealand Copepoda. . 103 



Genus Xouthous, n. gen. 



Body conical, rounded in front. Anterior antennae 7 -jointed, geniculate 

 in the male ; posterior pair with a small 3-jointed secondary branch. Man- 

 dibles with a large 2-branched palp. Anterior foot-jaws small, posterior 

 rather large and bearing an elongated claw. First pair of feet with the 

 inner branch 2-jointed ; outer 3-jointed. Next three pairs with both 

 branches 3-jointed ; fifth pair 2-jointed. 



Perhaps this genus should only rank as a sub-genus of Dactylopus, to 

 which it is most nearly allied, but besides being very different in its general 

 appearance, it differs in the structure of the mandibles, and of the first and 

 fifth pairs of feet. 



1. Xonthous novm-zealandia, n. sp. PL X., figs. 8-15. 



Body rather short, narrowing posteriority ; abdomen not very distinctly 

 separated from thorax. When seen laterally, the body is flat on the ventral, 

 but convexly arched along the dorsal surface. Head merged with first 

 segment of thorax. The integument is very dense and opaque, except at 

 two spots in the front of the thorax, where it becomes diaphanous, and pre- 

 sents the appearance of two lateral eyes. A red spot at each of these 

 lateral eye-spots probably marks a rudimentary eye, while the median eye 

 appears to be wanting : if present, it would be useless, on account of the 

 opacity of the carapace. The anterior antennae are much shorter than the 

 cephalothorax and lie in a groove on its under surface ; in the male they 

 are strongly geniculated and swollen, and the terminal joints act like an 

 opposable thumb or claw ; in the female, they are stout at the base and taper 

 to the extremity. 



The posterior antennae are strongly developed, as large as the anterior, 

 and bear a small, 3-jointed, secondary branch, which is terminated by two 

 long slender setae. Mandible-palp forming a two-branched appendage, the 

 larger branch bearing two stout plumose spines and two terminal setae. 

 Maxillae small, (?) palp apparently slender, and bearing two long setae. 

 Anterior foot-jaws small, bearing several marginal setose processes. Pos- 

 terior pair 2-jointed, terminated by a strong claw ; basal joint with a strong 

 spine. First pair of feet with inner branch elongated, 2-jointed, first joint 

 large, broad at the base and bearing a very long seta, second very short and 

 narrow, carrying two long setae, which are jointed near their apex ; outer 

 branch 3-jointed, considerably shorter than first joint of inner. Second and 

 third pairs of feet with both branches 3-jointed, inner branch the longer, 

 the individual joints broader and less setose than those of the outer. 

 Fourth pair of feet with both branches 3-jointed, subequal. Fifth pair 

 2-branched, outer branch 2-jointed (?), terminal joint bearing five subterminal 

 spine-like setae ; inner branch subquadrate, with five setae on its lower margin : 

 similar in both sexes. Caudal setae very short. 



