23 



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 cephaUc 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 joiiit a complicated apparatus arises, which when 

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

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

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

 animal can fold up upon itself hke 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 

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

 underneath the head in the same manner as a butterfly folds its pro- 

 boscis, but when in pursuit of the female they become extended at 

 full length and present a very beautiful appearance. 

 Five species of this genus have now been described. 



1. Chirocephalus DiAPHANUS, Prevost. Antennis inferiuribus 

 maris validis, cylindricis, apice acuminatis, jjrocessu dentato 

 ad basin articuli secundi armatis ; fronte rotundato. 



Long, maris 14 lin., fceminse 1 poll. 



Pro Synonymis \'ide " Baird's Nat. Hist, of the British Entomos- 

 traca, Ray Society, 1850." 



Hab. In Angha, Gallia, prope Genevam, &c. &c. 



This species, which occurs in many places in England, as well as in 

 France, Switzerland, &c., is very elegant in form, and (the male more 

 especially) very beautiful in colour. It is upwards of an inch in length, 

 slender, of a cylindrical form, and nearly transparent. In the male 

 the inferior antennae or cephalic horns are of a beautiful translucent 

 bluish green colour, tipped at the extremity with a fine red hue. 

 The caudal fins are of a bright red. The female has a strip of blue 

 along the whole length of the back, and the ovarian bag when full 

 of ova is conical in shape and of a reddish brown. The inferior an- 

 tennae of the male are very strong organs, divided into two joints ; 

 the basal joint is thick and fleshy, and the terminal joint is cylindri- 

 cal and curved in the form of a horn, having at the base where it 

 joins the first joint a flat plate attached to it, beset with several stout 

 teeth. The apparatus which we find at the base of the first joint, 

 consisting of the long, flat, somewhat tapering body with its digiti- 

 form and fan-shaped appendages, is of a very delicate transparent 

 bluish green colour. The antennae of the female are short, stout, 

 pointed at the extremity, flexible, and slightly curved downwards. 



2. Chirocephalus lacuna;, Guerin. Antennis inferiorihus 

 maris validis, valde arcuatis, articulo hasali magno, dentato, 

 terminali cylindrico, ad apicem sinuato. 



