THE CANADIAN ENTOMOLOGIST. 333 



DIPLONYCHUS, LAPORTE ( = HYDROCYRIUS, SPINOLA), 



AND ITS RELATION TO THE OTHER BELOSTO- 



MATID GENERA. 



BY J. R. DE LA TORRE BUENO, NEW YORK. 



The genus Hydrocyritis was founded in 1850 by the Marquis 

 MaximiHan Spinola/ and since then it has figured under that name. 

 It has been redescribed several times under different appellations. Siai 

 called it Ilyotrephes f A number of other authors^ have treated it as a 

 species of the old genus Belostoma, Auctt. (now Amorgius, Stki). But the 

 question nevertheless arises, '• Is this the true generic name, or have we 

 another valid appellation for the genus.?" In consulting a number of 

 works and papers for material for these notes on the affinities of 

 Hydrocyrius, Laporte de Castelnau'b* definition of the genus Diplotiychus 

 attracted my attention. It reads thus : " Antennae breves, sub oculos in 

 excavatione insertae, articulis 4 ; ultimis 3 subpectinatis. Rostrum breve, 

 arcuatum, acuminatum. Tarsi articulis 2 ; ungulis 2. 



" Facies des Belostomes; I'abdomen des femelles est termine' par deux 

 longs filets. 



" ler Sous-genre. Diplonychus^ Mihi. 



" Corpus elongatum ; tarsoruni anticorum unguiculis elongatis. 

 Belostoma rustica, Fab., 106, 3. 



" Et plusieurs autres especes exotiques. 



" lime Sous-genre. Sphce.rodema. Mihi, etc." 



Further on in the same work (p. 83) he states : " C'est par erreur que 

 j'ai indique (page 18) le Belostoma rustica de Fabricius, comnie type du 

 genre Diplonic/ius (!). Get insecte' est un SphcerodemaP 



Now, according to my understanding of Kirkaldy's views on the 

 historical method of type fixation,'' this leaves the subgenus without a type 

 species. The fact that subsequent authors have raised the sub- 

 genus to full generic standing, and that under it they have grouped 

 Belostomatids with two sJiort claws, in no way invalidates the original 

 description, which specifically indicates that in the typical subgenus 

 Diplonychus the claws of the anterior tarsi are elongate. Moreover, the 



1. 1850, Mem. Mat. Soc. Modena, xxv, 146. 



2. 1856, Ofv. Vet. Ak. P'orh, p. 358. 



3. Dufour, Belostoma algeriense ; Lucas, B. grande ; Guerin, B. capitatum; 

 Coinde, B. cosmopolitanum. 



4 1832, Essai d'line Class. H^m. p. 18 (of separate). 

 5. 1905, Proc. Ent. Soc' Wash., Vol. XII, pp. 27 to 28. 

 October, 1907 



