Hale — Aquatic Hemiptera 399 



The ovipositor is very similar in these six species and is of the same character 

 ill Buenon margaritacea, the life history and biology of which have been dealt 

 with by Prof. Hnngerford. f^) This author also figures the drilling gonapophyses 

 of several Notonectae, and while these show specific differences it is probable that 

 throughout Anisops and Biienoa the ovipositor is of common form. 



The ova of Notonectids are elongate, an"d if merely glued to plants are 

 attached by the long axis ; the eggs of Corixids are not elongate, are often peg-top 

 shaped, and either pedicellate (as in Arctocorisa mercenaria and Porocorixa 

 eurynome) or attached at the base to a gelatinous pad (pi. x, fig. 4, 5). 



in Ayii&ops, considerable dimorphism is exhibited between the sexes. The 

 single-jointed anterior tarsi of the male terminate in curved, flattened and rather 

 blunt claws, and the anterior tibiae are expanded basally on the inner surface 

 to form a spur, on which is situated a stridulatory comb (fig. 362,s). The female 

 differs from the male in having the anterior tarsi two-jointed, with sharper and 

 more slender claws, while the form is usually more robust, the eyes slightly 

 smaller, the notocephalou wider, and the pronotum a little shorter. 



In the allied American genus, Buenoa, the male has a tibial spur quite similar 

 to that of Anisops, and, in some species at least, a femoral area, on which the comb 

 apparently operates. Hungerford describes and figures this apparatus, and 

 mentions that, in addition, there are stridular areas on the face at the base of the 

 beak. In the males of the Australian species of Anisops the femoral area is not 

 apparent, but the rostrum is produced on each side to form a chitinous prong; 

 when the anterior legs arc folded, the position in which stridulation is effected, 

 the apex of each prong is in juxtaposition with the tibial comb (fig. 362), so that 

 it would seem that sound is produced by the rubbing of the combs on these rostral 

 prongs ; the beak is less markedly pronged in the male of Buenoa. 



The genera at present known from Australia may be distinguished as 

 follows: 

 a. Abdomen Avith a median, ventral carina; hem- 

 elytra overlapping posteriorly ; legs dissimilar ; 



eyes large Sub-family Notonectinae. 



b. Anterior tarsi of male single-jointed . . Anisops. 

 bb. Anterior tarsi of male two- jointed. 



c. Pronotum short, with the anterior 



angles excavate Enithares. 



cc. Pronotum moderately long, the an- 

 terior angles not excavate Notonecta. 



aa. Abdomen without median, ventral carina; elytra 

 not overlapping posteriorly ; legs similar ; eyes 

 rather small Sub-family Pleinae. Plea. 



(2) Hungerford, Bull. Univ. Kansas, xxi, 1919. 



