6G8 CRUSTACEA. 



The inner antennas consist of a long cylindrical, three-jointed, basal 

 portion, a little longer than the beak of the carapax ; the . first two 

 joints nearly equal, the third short and smaller. Flagellum very 

 slender, whole length more than one-half the length of the body. 



Three pairs of legs developed ; all two-branched, branches unequal, 

 the outer consisting of five joints, with a pencil of hairs at the ex- 

 tremity; the second of the three pairs largest. Posterior to these 

 three pairs there were tubercles or rudiments of four more pairs. 



FAMILY III. LUCIFERID^. 

 GENUS LUCIFEK, Thompson. 



Corpus valde attenuatum, segmento antennali elongate, tenui. Antennce 

 totce flagellis longis confectce; externce squamd basali instructce. 

 Pedes tJioracis numero decim, longi, non bifidi, duo antici valde re- 

 plicati, 8 sequentes prorsum parce flexi; alii quatuor posteriores nor- 

 males obsoleti. Pedes abdominis bene natatorii. 



Body very much attenuated, antennary segment elongate, slender. 

 The four antennae with long flagella, outer pair with a basal scale. 

 Thoracic feet ten in number, not two-branched, the two anterior 

 each folded back upon itself, the eight following thrown forward; 

 posterior to these, two normal pairs are obsolete. Abdominal feet 

 large and natatory. 



The long antennary segment is like a slender neck, and is usually 

 separated from the proper carapax by a suture, more or less distinct. 

 It is without a beak, or has but a short one, and has a spine in front 

 on either side. It bears two pairs of antennas and long eyes, as above 

 described. The first basal joint of the inner antennae is not shorter 

 than the eyes; the next two joints are quite short. The base of the 

 outer antennas is very much shorter than that of the inner. The 

 flagella of both pairs are slender, and consist of long joints. The 



