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distinctly separated in the middle; pigmented ocular rodes far remote from the 

 corneal lenses and converging to a point placed about in the middle of the an- 

 terior division, near the ventral face; each provided at the distal end with a highly 

 refractive body. 1 ) 3rd trunkal segment produced on each side to an acute 

 posteriorly-pointing lappet; 4th segment much smaller than the preceding one, 

 and in some cases confluent with it dorsally. Tail composed in both sexes of 

 only 2 segments, which in some cases are imperfectly separated. Caudal rami 

 narrowly produced, with 2 unequal spiniform apical setae accompanied by a 

 slender sub-dorsal bristle. Anterior antennae short, 6-articulate. Posterior an- 

 tennae powerfully developed, especially in male, 3-articulate ; middle joint rather 

 dilated; terminal joint very mobile and tipped with a slender claw. Maxillae 

 armed at the extremity with a bifid movable claw, inside which a likewise 

 movable spiniform appendage coarsely pectinate on the outer edge is attached; 

 palp comparatively small, scale-like. Anterior maxillipeds short, with the termi- 

 nal part imperfectly defined from the basal one and exserted to a curved claw, 

 having moreover at the base inside 2 or 3 unequal pectinated setae. Posterior 

 maxillipeds distinctly 3-articulate, the last 2 joints forming together a clawed 

 hand more strongly developed in male than in female. The 3 anterior pairs 

 of natatory legs with both rami 3-articulate, the outer one much the larger 

 and rather produced, being armed outside and at the tip with strong denticulated 

 spines. 4th pair of legs much feebler in structure, with the inner ramus reduced 

 to a single small joint. Ovisacs in female attached dorsally and in some cases 

 confluent. 



Remarks. This genus was established by Dana as early as the year 

 1845, and is the type of the present family. The genus Agetus of Kroyer is 

 identical with Dana's genus. It comprises a great number of species chiefly 

 occurring in southern latitudes. No less than 20 different species have been 

 enumerated by Giesbrecht in his great work; but some of these are more 

 properly referable to the nearly-related genus Corycella Farran. Off the Norwegian 

 coast only a single species has as yet been observed, to be described below. 



J ) I am however by no means convinced that the above-mentioned parts, as generally 

 opined, are in reality visual in significance, but should be much more inclined to suppose, that 

 they constitute a peculiarly modified photogenous apparatus for projecting condensed light forwards, 

 like the light-projectors of our automobiles. To settle this question, observations on living 

 specimens would be needed. 



