408 PROCEEDINGS OF THE NATIONAL MUSEUM vol. iii 



sternum somewhat swollen, carinate along midline, with numerous 

 long hairs. 



Metapleuron: Weakly convex; terminal process of peritreme large, 

 elongate-oval, surface alutaceous but shining, with one to three 

 longitudinal or oblique sharp rugae (fig. 89) ; evaporatorium extensive, 

 distinctly surpassing apex of peritreme and reaching almost to 

 posterior coxae; lateral area with numerous coarse, rugose punctures. 



Legs: Moderately long; anterior tibia (fig. 116) not surpassing 

 tarsal insertion, strongly compressed, dorsal margin with eleven 

 spines; middle and posterior (fig. 139) legs with tibia terete; tarsal 

 II little shorter than I, III longest. 



Sternites: Strongly convex, punctured, laterally more coarsely 

 punctured and with numerous sm^all tubercles; posterior margin of 

 each segment finely denticulate or crenulate. 



Terminalia: Male genital capsule opening dorsally, apical rim 

 feebly flared. 



Type of genus.— Cydnus tristis Fabricius (1803, p. 195), by sub- 

 sequent designation by Blanchard "(1844, p. 505)" (vide China, 

 1943, p. 220); Fabricius' name is a synonym of Cimex aterrimus 

 Forster (1771, p. 71). The type of Brachypelta is Cydnus tristis 

 Fabricius (loc. cit.), monobasic. Thus, because Brachypelta has the 

 same type as does Cydnus, it is a synonym by isogenotypy. 



Distribution. — The single species of the genus Cydnus is a 

 Palearctic form which, according to Oshanin (1912), occurs in all the 

 major zoogeographical regions of the Old World. The present records 

 of it in the Western Hemisphere probably represent introductions 

 rather than a part of the permanent range. 



DiscussiON.^ — ^The occurrence of the single species of this genus in 

 the Western Hemisphere came as a surprise. Although the author 

 prefers to consider these records as accidental introductions and not 

 indications of established population, he believes that if the latter 

 does prove to be true this information will be useful. 



Cydnus aterrimus {Forster) 



Plate figures 4, 21, 89, 114, 116, 139, 167, 172, 186, 200 



Cimex aterrimus Forster, 1771, p. 71. 

 Cimex tristis Fabricius, 1775, p. 716. 



Diagnosis.' — This is the only species known to belong to the genus 

 Cydnus. 



Description. — Based on two males. Male: Elongate-oval, sides 

 parallel. 



Head: Length four-fifths width, 1.71(1.63-1.79) :2.02(1.96-2.08); 

 in terocular width, 1.43(1.36-1.50); anterior outline more than a semi- 

 circle, broadly V-marginate at apex; juga much surpassing and 



