13 



as the inner. Anterior antennae much more elongated than in the preceding 

 species, about equalling in length the cephalic segment, and composed of 18 well 

 defined joints, 3rd joint much the largest, 6th joint exhibiting a slight indication 

 to be subdivided into 3 joints. Posterior antennae with the terminal joint fully 

 as long as the 2 preceding joints combined. Natatory legs with the seta attached 

 inside the 1st joint of the inner ramus remarkably strong, especially in the 2 

 posterior pairs; terminal joint of outer ramus in 4th pair with only a single 

 spine outside, the distal spine being replaced by a thin bristle abruptly bent 

 inwards. Last pair of legs of comparatively feeble structure, and composed each 

 of 3 joints, the first 2 somewhat lamellar and finely ciliated inside, middle joint 

 carrying outside the usual bristle, last joint comparatively small, and provided 

 with 4 slender ciliated setae, the innermost of which is the shortest. Ovisacs of 

 moderate size and slightly divergent. 



Male, as usual, smaller than female, and easily recognizable by the strongly 

 hinged anterior antennae. Last pair of legs differing from those in female in 

 being 4- articulate, the last joint being subdivided into 2 well defined joints, the 

 proximal of which carries on each side a seta, whereas the distal joint has 4 

 setae on the tip. 



Body semipellucid, with scattered opaque patches of a whitish or yellow 

 colour, in some cases, moreover, exhibiting a fine rosy tinge on several parts of 

 the body, as also partly on the anterior antennae. 



Length of adult female 0.70 0.90 mm. 



Remarks. This form has generally been recorded under the specific 

 name littoralis proposed by Brady. As, however, the name longicornis, assigned 

 to this species by Boeck, dates from the very same year, and is a much more 

 adequate name, I have found it suitable to prefer that name to the one proposed by 

 Brady. For the present species cannot in reality be said to be, like the preceding 

 one, a strictly littoral form, as it more generally occurs in greater depths and 

 is only quite occasionally met with in the littoral region. I have found that 

 such specimens are of smaller size and have the caudal rami less elongated than 

 in the typical form, thus more properly constituting a particular variety, for 

 which the name littoralis may be retained. 



The present species is easily distinguished from the preceding one by the 

 more slender form of the body, the much more elongated anterior antennae, and 

 the somewhat different shape of the caudal rami. In the structural details also 

 some well-marked differences are found, especially as regards the structure of the 

 last pair of legs. 



Occurrence. I have found this form rather frequently in many places of 



