114 BRITISH ENTOMOSTRACA. 



its appearance, an organ so large in the adult, that Miiller 

 says " its head is all eye."* 



The males have never yet been noticed by any observer. 



Hah. — Ditch near Richmond, on the banks of the 

 Thames, nearly opposite Isleworth, July. It seems to be 

 very limited in its range of habitat, for though this ditch 

 is frequently filled by the tide from the river, and is fully 

 a mile in length, I have only found it in one spot, not 

 much above twenty yards in extent. 



Genus 2 — Evadne. 



EvADNE, Loveii, Zoologisk. Bidrag., p. 1. 



— M. Edwards, Hist. Nat. Crust., iii, 390. 



— Goodsir, Edin. Phil. Joiirn., xxxiii, 366. 



Character. — Head not distinct from the body. Abdo- 

 men short, scarcely projecting from the shell. 



1. Evadne Nordmanni. Tab. XVII, fig. 2. 



Evadne Nordmanni, Loven, Zoologisk. Bidrag., 1. 1, 2 ; Do., Kougl. 

 Yeteuskaps. Acad. Hadlingar., t. 1, f. 1-8. 



— M. Edwards, Hist. Nat. Crust., iii, 390, t. 36, f. 7. 



— Goodsir, Edin. Phil. Jouni., xxxiii, t. 6, f. 15, 16. 



The whole animal is almost colourless, except the poste- 

 rior part of the eye, which is black. The anterior portion 

 is much the larger, and deeply ribbed longitudinally. 



Antennae composed of two branches. A number of 

 long setae spring from the extremity of each. 



The legs (t. XVII, f. 2 a) are four pairs, and arise 

 almost immediately below the eye. They are each com- 

 posed of four articulations, which are all furnished with 

 several strong setse. A powerful muscle extends from the 

 legs, and passing upwards immediately behind the eye, is 

 attached to the dorsal portion of the shell. The whole 



* " Caput totum oculus." — Entomost., IIS. 



