Zoological Society. 221 



inch. The inferior antennae or cephalic horns in the male are large 

 and tortuous ; they are composed of three joints ; the first or 

 basal joint is the largest, is cylindrical, and extends for some distance 

 straight forwards ; the second, smaller than the basal, is also cylin- 

 drical, curves slightly at first, then bends suddenly backwards upon 

 itself ; the third or terminal joint bends as suddenly forwards and 

 terminates in a club-shaped extremity, which divides into two 

 branches, one longer than the other, terminating in a long filiform 

 process ; the other flatter, shorter, and dividing into two shorter fili- 

 form processes of unequal length. The antenniform appendage is 

 long and cylindrical, rather stout, and springs from close to the ex- 

 tremity of basal joint. The basal joint is destitute of the lanceolate, 

 toothed appendage on internal edge, which we see in the preceding 

 species. The superior antennae are long and slender, and consist 

 of two joints, the basal one much shorter than the second. The 

 male organs are rather long, cylindrical, and of a horny texture. 

 The front of the head is prolonged into a beak, which is flat, rather 

 broad and slightly lobed at the extremity. Feet short. Abdomen 

 slender. Caudal appendages of moderate length, and beset on each 

 side with numerous short and plumose setae. 



The cephalic horns in the female are short, thick, and terminate in 

 a short spine at the extremity. The ovarian bag is conical, acute, 

 and the ova are of an ochreous colour. 



The chief differences between this species and S. cafer consist, in 

 the male, in the shape of the front of the head, the organs of gene- 

 ration, and in the inferior antennae having no lamina with teeth on 

 the ba-al joint ; in the female, in the shape of the external ovary. 



Genus Chjrocephalus, Prevost. 



Corpus molle, cylindricum ; segmentum caudate pinnis chiabus 

 ciliatis instructum ; pedes undecim ; antennae inferiores maris 

 va/idce, biarticufafre, appendicibus digitifurmibiis ftabettiformi- 

 busque armatce. 

 This genus closely resembles the two preceding in the shape and 

 form of the body, having the same number of articulations, possess- 

 ing the same number of feet, and having similar caudal fins. It is 

 in the structure of the inferior antennae or cephalic horns in the 

 male, that the important difference between the two genera exists. 

 These antennae are very large, and are composed of two joints. At 

 the base of the first joint a complicated apparatus arises, which when 

 unfolded presents a very curious appearance. This consists of a long, 

 flat, curved, verv flexible body, somewhat tapering and toothed on 

 its edges, and composed of numerous short articulations, which the 

 animal can fold up upon itself like a ribbon. Springing from its ex- 

 ternal edge near the base are four rather long and flexible appendages 

 strongly toothed on their internal edge, somewhat resembling long 

 fingers, and in addition to these a large membranous triangular- 

 shaped body, toothed on its edges all round, which when extended 

 nearly covers the finger-like bodies, and can be folded and unfolded 

 like a fan. When the animal is at rest these organs are folded up 



