170 ISOTOMA. 



" Length '05 inch. 



" In some varieties a double row of black points 

 down the back. 



" Extremely common at Cranmore, on the surface 

 of little pools of stagnant water. March, 1808." 



Sweden, France, England, Ireland. 



Isotoma aquatilis. 



Isotoma aquatilis, Muiler. Zool. Dan. Prod. 



— trifasciata, Bourlet. Mem. Soc. Roy. Lille, 1839. 



— bifasciata, „ „ „ „ 

 Podura trifasciata, „ „ „ Douai, 1842. 



— bifasciata, „ „ „ „ 

 Desoria riparia, Nicolet. Mem. Soc. Helv., 1842. 



— - — Gervais. His. Ins. Apt., vol. iii. 

 Isotoma bifasciata, „ ,, ,, ,, 



— trifasciata, „ „ ,, „ 



— riparia, Nicolet. Ann. Soc. Ent. France, 1847. 



— bifasciata, „ „ „ ,, 



— lineata, Lubbock. Trans. Linn. Soc, 1862. 



— riparia, Poratli. Of. af. k. Veteusk.-Akad. Forh., 1869. 



Plate XXXVII. 



Muiler' s description of this species is as follows : — 

 " Cylindrica, flavicans, oculis, lateribusque abdominis 

 nigris." 



It appears to have been next observed by Bourlet, 

 who says, " 2 millim. Verdatre, trois fascies macu- 

 laires longitu din ales noires sur le dos. 



" Verdatre en dessus, d'un gris jaunatre en dessous. 

 Les trois bandes maculaires dorsales commengait au 

 bord anterieur du thorax et se continuent parallelement 

 jusqu'au troisieme segment abdominal inclusivement ; 

 celle du milieu plus marquee que les autres. Corps 

 parseme d'autres taches de la meme couleur et de taches 

 ferrugineuses, principalement sur les cotes et sur la 

 tete ; queue jaunatre, tarses et antennes d'un gris 

 fauve ; corps pubescent." 



The segments of the antennae are subequal, and the 

 spring reaches forwards as far as the ventral tube. 



