222 Zoological Society. 



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 inferioribus 

 maris validis, cytindricis, apice acuminatis, jjrocessu dentato 

 ad basin articuli secundi armatis ; f route rotundato. 



Long, maris 14 lin., fceminae 1 poll. 



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

 traca, Ray Society, 1850." 



Hab. In Anglia, 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 (tbe 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 b right 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 lacunae, Guerin. Antennis inferioribus 

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

 terminali cylindrico, ad apicem sinuato. 



Long, maris et fceminae 12-15 millim. 



Branchipus lacunae, Guerin, Iconog. Regn. Anim. Crustace's, 39. 

 t. 33. f. 4, 4 a. 



Hab. In stagnis prope " Fontaiuebleau ; " M. Guerin. 



This species, which is briefly described by M. Guerin in the ' Icono- 

 graphie du Regne Animal,' is found in little pools of water near Fon- 

 tainebleau. It is transparent, but is smaller than the preceding spe- 

 cies, and is distinguished from it by the shape of the inferior antennae 

 or cephalic horns in the male. These organs are of two joints ; the 

 basal one large, and armed on its internal edge with several stout 

 teeth or lobes ; the second much smaller, cylindrical, bent suddenly 

 back upon the first, and sinuated, or as it were slightly toothed at 

 the apex. The long ribbon-like appendage which springs from the 

 base of the first joint appears to have only two very short processes 

 attached to it, instead of the four long finger-like bodies, and the 

 fan-shaped body is not represented at all ; but this part of the head 



