J01_ 



end; dorsal seta likewise attached near the end; apical setae 3 in number, the 

 innermost very small, the middle one the longest, though only slightly exceeding 

 the ramus in length. Anterior antennae very slender and attenuated, exceeding 

 somewhat in length the cephalic segment,[and composed of 8 well defined joints 

 clothed with scattered comparatively short setae, each antenna carrying more- 

 over 5 well developed aesthetasks, one attached in the middle of the 4th joint, 

 2 to the end of the 5th joint, and 2 to the tip of the very slender terminal 

 joint. Posterior antennae with the basal part- distinctly subdivided, terminal 

 joint comparatively narrow, with the number of spines and setae reduced; outer 

 ramus replaced by 2 juxtaposed ciliated setae of equal length. 1st pair of legs 

 wanting the usual spine inside the 2nd basal joint; outer ramus imperfectly 

 developed, only consisting of a single narrow linear joint, not even extending 

 to the middle of the 2nd joint of the inner, and without any spines outside. 

 The 3 succeeding pairs of legs with the 2nd basal joint bent outwards at an 

 angle with the 1st; both rami distinctly triarticulate and very narrow, the inner 

 one being the longer; 1st joint of outer ramus nearly as long as the other 2 

 combined and in 2nd pair wanting the usual spine outside. Last pair of legs 

 with the distal joint about 3 times as long as the proximal one and very 

 narrow, carrying 6 slender marginal setae, 2 on the outer edge and 4 on 

 the apex. 



Colour (according to Giesbrecht) whitish grey, with a slight rosy tinge. 



Length of the specimen examined 1.24 mm. 



Remarks. This is the species first described, and may accordingly be 

 considered as the type of the present genus. It is closely allied to the form 

 recorded by Brady from the Challenger Expedition under the name of Oonio- 

 psyllus rostralus, which, as stated by Giesbrecht, is another species of the same 

 genus, differing from the one here described in the comparatively shorter 

 caudal rami, as also somewhat in the structure of the antennae. In Brady's 

 species the anterior ones are only composed of 7 joints, and the posterior 

 one have only a single seta in the place of the outer ramus. 



Occurrence, A solitary female specimen of the present form was found 

 in a sample taken, many years ago, in the upper part of the Christiania Fjord. 

 This is the only instance of the occurrence of the present form off the coasts 

 of Norway. I have never met with it subsequently. 



Distribution. Irish Sea, Atlantic Ocean, Mediterranean, Gulf of Guinea, 

 Indian and Pacific Oceans. 



15 Crustacea. 



