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XV. Note on the British Species belonging to the Genus 

 Acanthosoma, Curt. By W. S. Dallas, Esq., F.L.S. 



[Read January 6th, 1851.] 



The genus Acanthosoma, established by Curtis in 1824, upon the 

 Cimex hcemorrholdalis, Linn., includes five European species, of 

 which only four are found in this country. Notwithstanding the 

 small extent of the genus, however, the synonymy of the species 

 contained in it is by no means settled, and that of two of them in 

 particular is in a very confused and unsatisfactory state ; almost 

 every author, in fact, who has had occasion to touch upon them, 

 having departed more or less from all that had been previously 

 published on the subject. Under these circumstances I have 

 endeavoured, by careful examination and the inspection of the 

 Linnaean cabinet, to arrive at some satisfactory conclusion on the 

 subject, and I hope in the present paper to be able to set the 

 matter on a more secure basis than it has hitherto occupied. 



Genus Acanthosoma. 



Cimex, p. Linne, De Geer, Fabricius, Schrank, Fallen. 



Pentatoma, p. Latreille, Le Pelletier et Serville. 



Acanthosoma, Curtis, Herrich-Schaffer, Burmeister, Amyot et 



Serville, Sahlberg. 

 Clinocoris, Hahn. 



Head rather small, with the central lobe as long or longer 

 than the lateral ones. Antennse five-jointed. Rostrum slender, 

 reaching the base of the abdomen. Membrane of the elytra with 

 longitudinal nervures. Sternum with a large central keel, which 

 is attached to the mesosternum, and projects forward nearly to 

 the base of the head. Abdomen with a long spine at the base, 

 which runs up at one side of the sternal keel. Scutellum trian- 

 gular, with the sides nearly straight. Tarsi of two joints. 



Amyot, in his " Entomologie Francaise," published in the 

 " Annales de la Societe Entomologique de France," having made 

 use of characters drawn from the shape and proportionate size 

 of the different parts of the external sexual organs, to assist in 

 the determination of the species, some account of the structure 

 of these parts may be acceptable to the British Entomologist, 

 although the species present a sufficiency of obvious characters 



