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Art. VI. — History and Anatomy of the Hemipterous Genus Belostoma. 



By Joseph Leidy, M. D. 



Belostoma is a genus of hemipterous insects, belonging to the section Heteroptera, 

 family Hydrocorisa, found in all the warmer parts of the globe, aquatic in habit, and 

 eminently rapacious. It was separated by Latreille, from the Linnaean genus Nepa, 

 founded upon the antennse having four articulations, of which the terminal three are 

 pectinate, and all the tarsi bi-articulate and nearly alike. 



DESCRIPTION. 



Belostoma : body sub-elongated, lanceolate, flattened superiorly ; abdomen flattened inferiorly with the 

 central part abruptly carinated ; pro-thorax and head depressed. 



Head, sessile, triangular in outline ; promuscus inferior, inflected, conical, quadriarticulate ; first articulation 

 permanently fixed to the clypeus, the others moveable. Between the first and second articulations, 

 there exists a quadrangular opening, communicating with the interior of the vagina, ordinarily closed 

 by the apposition of the ligula. Labrum small, ovate, posteriorly received into a notch of the clypeus, 

 anteriorly enclosed by the first articulation of the promuscus. Ligula received within the vagina. 

 Eyes large, prominent, distant, triangular in outline, ciliate at the posterior edge. Antenna? very short, 

 pectinate, infra-ocular, ordinarily concealed within a short deep groove ; quadriarticulate ; terminal three 

 articulations furcate, and ciliated ; one branch of the terminal articulation with a short, prominent 

 spine. 



Thorax. Prothorax : Pronotum quadrate, smooth, convex ; lateral margins compressed, convergent, and 

 curving beneath, forming a concave infero-lateral plate bounding the anterior acetabula externally. 

 Prosternum depressed, carinated at the anterior part. 



Mesothorax : ScuteUum large, extending as far back as the second abdominal segment. Scapulae 

 projecting as far back as the commencement of the abdomen, and supporting on the supero-external 

 border, a tubercle or catch, which fits into a corresponding socket on the under surface of the marginal 

 rib of the hemielytra. 



Metatiiorax : Metastemum hexagonal. 



Hemielytra somewhat shorter than the abdomen and smooth, with the exception of an elliptical patch of 

 fine pubescence a few lines from the membranous portion. Alae shorter than the hemielytra. 



Legs : Anterior pair raptorious ; intermediate and posterior pair natatory. Coxae free, large, and robust. 



Trochanters large ; anterior pair notched externally for the i-eception of the unguis in the repose of the 



anterior legs ; intermediate and posterior pair fulcrant. Thighs large ; anterior pair clavate and very 



robust, anterior face (when the legs are advanced) densely and finely pubescent, with a double groove 



and intermediate ridge for the accommodation of the tibia in repose, or perfectly entire in one species ; 



intermediate and posterior pair ciliated posteriorly with respiratory hairs. Tibial : anterior pair 



narrow, and curved, with a groove upon the inner side except in one species, in which they are entire ; 



posterior pair very compressed, broader than the thighs ; intermediate and posterior pair fringed on the 



inner and outer edge by respiratory hairs. Tarsi dimerous : posterior compressed. A single unguis 



to the anterior tarsi ; two to the intermediate and posterior tarsi. 



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