338 THE CANADIAN ENTOMOLOGIST. 



The egg-laying habits oi Dip iony chits ate as in Belostoma,^'' in which 

 genus (as well as in several others of the family) the female fastens the 

 eggs on the back of the male. A?norgius, however, deposits its ova under 

 a convenient log or plank in a damp spot at the water's edge, glued to it, 

 which also appears to be the habit with Benacus}^ To recapitulate : 

 Diplonychus, Lap. (Bueno), approaches Belostoma, Latreille, in the shape 

 of the eyes, the genital plate, the posterior and the intermediate tibiae, and 

 in the manner of oviposition. It is close to .^///(^r^/;/^, Stai, in the form 

 of front and vertex, general shape, anterior femora, tibis and tarsal joints, 

 and in the claws in the nymph. It is intermediate in the rostrum, which 

 tends to the Amorghts side. It resembles both genera in the shape of the 

 scutellum, in the membrane, of the hemelytra, and in most of the other 

 features not dwelt upon. The differences are the general shape of the 

 head, which is very broad, the shape of the pfothorax, and, above all, in 

 the possession of two long claws in the adult, of equal length in one 

 known species, and unequal in the other two. From this last character, 

 taken in conjunction with the nymphal structure of these appendages in 

 the two allied genera, as well as in the others of the family, we may in 

 fairness conclude : ist. That Diplonychics is an intermediate form in the 

 chain of development linking the Amorgioid forms to the Belostomoids ; 

 and 2nd. That it is in all likelihood the most primitive form of the 

 Belostomatid series, from which arise the genera Amorgius, Stai, and 

 Be7iaais, Stai, on the one hand, and Beiostoma, Latr.; Abedus, Mayr ; 

 Liffifiogetof^, Mayr; Sphcerodema^ Lap., and Nectocoris, Alayr, on the other. 



To sum up, it would appear that Diplonychiis, Laporte (Bueno), is 

 nearly allied to both Belostoma, Latr,, and Amorgius, Si'al, with closer 

 leanings to the latter, and that its systematic position is as given in the 

 linear arrangement between these two genera. 



III. 



The species and distribution of Diplonychus, Lap. (Bueno), are moot 

 questions. A great deal of confusion has arisen from the description and 

 rediscription of what is said to be one species from several widely-separated 

 localities. I recognize three species, but it is more than likely that some 

 of those reduced to synonymy may be later revived as our knowledge of 



17. 1906, Bueno, op. c. p.; 1900, Horvath in Lit., quoted by Mont. Bull. Soc. 

 Sci. Buc. An. IX, No. 2 and 3, p. 8, 



18. 1889, C. M. Weed, Studies in Pond Life, Bull. Ohio Agr, Exp. Sta., 

 Tech. ser., I, No. i ; 1907, Needham, Ent. News, X\'III, pp. 113 to 116. 



