232 THE ENTOMOLOGIST. 



scutellum, except in Micronecta, where the sciitellum is almost 

 entirely exposed. The tegmina (elytra) are usually ornamented 

 with more or less regular, vermiculate or straight, transverse 

 lines, these being often broken up into series.* In Micronecta, 

 &e., there are few markings, these being generally more or less 

 longitudinal and generally more or less obscure. In Micronecta , 

 Cymatia, and Corixa, the tegmina, and also the pronotum, are 

 more or less smooth and polished, sometimes punctured ; but in 

 the other genera these parts are either partly, or wholly, very 

 finely rastrate (i. e. striated like a file, this character being seen 

 best in an oblique position). The anterior legs and their stridu- 

 latory areas have already been described and figured by me f ; 

 the intermediate legs are long and slender, and are terminated 

 by two long claws ; the proportionate lengths of these parts form 

 good secondary characters for the discrimination of certain 

 species. The posterior legs are modified for swimming, even 

 more than are those of the Naucoridfe ; they are flattened, 

 dilated, and thickly fringed with ciliate hairs. 



In the females the abdominal segments are regular, but in 

 the males are broken up and disordered. The asymmetry is to 

 the left in Corixa, to the right in all the other genera. The 

 strigil has been discussed in my paper cited last. 



Although the Corixidae are so well known and have so often 

 been dealt with systematically, their biology has been little 

 studied in detail. 



The whitish ova of Corixa geofroyi are to be found in any 

 suitable piece of water from March onwards to -June attached to 

 the stem or leaves of various pondweeds by means of a glutinous 

 substance ; the pedicle seems to be extensile. They are more or 

 less onion -shaped, the apical end being drawn out into a point. 

 They have been briefly described and figured by Dufour (p. 350, 

 pi. xvi. f. 186, under the specific name of striata), and by Leuckart 

 (1855, Miiller's Archiv. pi. viii. f. 23, as Coriza (/) striata). The 

 internal development of the egg has been studied by Metshnikov at 

 some length (1866, Zeitschr. Wiss. Zool. xvi. pp. 129 and 422-36, 

 pis. 26 and 27 a) ; a very brief 'precis is given by Packard (1898, 

 ' Text-book of Entomology,' fig. 493). Leuckart also describes the 

 egg of Arctocorisa nigrolineata, while Dufour describes that of 

 A. lateralis {hieroglypliica, Duf.) as being pointed, elongate oval 

 (fig. 187). The ova of A. mercenaria have been for centuries 

 used for food by the Mexicans ; while an Egyptian species, un- 



■•' This pattern is not modern, being well shown in " Corixa " clegans, 

 Schlechtendal (1894, Abh, Naturf. Ges. Halle, xx. 21G ; pi. xiii. f. 4), from 

 the Aqnitanian (Kainozoic) formations of the Siebengebirge in Germany. 



f See "The Stridulation of Corixa''' in Entom. xxxiv, 9 (1901), and 

 "The Stridulating Organs ofWaterbugs (Rhynchota), especially of Corixidas" 

 in Jom'n. Quekett Micr. Club (2), viii. 33-46, pis. 3 and 4, where other papers 

 are referred to. 



