110 Mr. W. S. Dallas's Note on the 



to enable them to be easily distinguished from one another, with- 

 out having recourse to any purely sexual character. The struc- 

 ture of the male organs, moreover, is very peculiar, and differs 

 considerably from the form usually observed throughout the 

 Pentatomidce. This peculiarity consists principally in the great 

 development of those organs which in other genera are con- 

 cealed beneath the ordinary anal plate, which usually closes the 

 aperture of the last ventral segment, but here becomes, as it 

 were, a seventh abdominal segment, and the space thus left at the 

 apex of the abdomen is occupied by the enlarged sub-internal 

 organs above mentioned, of which the dorsal portion is frequently 

 more or less produced on each side, and in some exotic species 

 projects considerably beyond the apex of the body. The female 

 organs consist, as in the other genera of the family, of five prin- 

 cipal plates, namely, two basal (pieces anterieures, L. Duf., pieces 

 basilaires, Amyot), divided from each other by a longitudinal 

 suture, and occupying the central emargination of the last ventral 

 segment, — two apical (pieces posterieures, L. Duf, pieces dernieres, 

 Amyot), forming the posterior and dorsal portion of the whole 

 apparatus, — and two intermediate (pieces intermediates, L. Duf. 

 and Amyot), which separate the basal from the apical plates, 

 but do not meet in the centre, the small notch thus left being 

 occupied by a small central plate, which is probably the apex of 

 some internal organ. 



A. Head pointed in front, central lobe projecting beyond the 

 lateral. Margins of the abdomen scarcely projecting beyond the 

 elytra, not variegated with black. 



a. Basal joint of the antennce projecting beyond the apex of the 

 head. 



Sp. 1. Acanthosoma hcemorrhoidale. 



Cimex hcemorrhoidalis, Linn. F. S. 925 (1761), and S. N. i. 



720, 35 (1767); De Geer, Mem. iii. 254, 3, pi. 14, fig. 7 



(1773); Schr. Enum. Ins. Aust. 267, 515 (1781), and F. B. 



ii. 70, 1099 (1801); Fab. E. S.iv. 98, 76 (1794), and S. R. 



160, 27 (1803); Don. Brit. Ins. vii. 5, pi. 218, fig. 2 (1798); 



Wolff, Ic. Cim. 10, tab. 1, fig. 10 (1800); Fall. Mon. Cim. 



44, 3 (1807), and Hem. Suec. 23, 3 (1829). 

 Cimex pabulinus, Harris, Exp. Eng. Ins. 88, pi. 26, fig. 2 



(1776). 

 Pentatoma hcemorrhoidalis, Le P. et Serv. Enc. x. 53, 1 (1825)- 



