STILBUM. 433 



moderately long and thick ; eves large, oval ; ocelli well developed, 

 the anterior ocellus placed in a hollow. Thorax massive, the pro- 

 notum concave anteriorly, the sides strongly convergent, the anterior 

 lateral angles of the prothorax prominent ; propleurae proportion- 

 ately larger in the d" than in the $ , excavate ; mesonotum and 

 scutellum convex ; mesopleurse broadly longitudinally grooved, 

 ' the margin anteriorly and the apical area depressed, the latter 

 bidentate ; the upper tooth broad, rounded at apex, the lower tooth 

 narrower aud more acute ; scutellum gibbous, with a medial little 

 hollow at base ; postscutellurn suppressed under the scutellum, 

 but from its base a large mucro, hollow above, projects backwards. 

 Wings ample : fore wing with the costal, medial and long 1st dis- 

 coidal cell complete, the 1st and 2nd submedial almost complete, 

 the radial cell open for its apical third ; hind wing nervures 

 present, but cells all unformed. Abdomen massive, transverse at 

 base ; the sides convergent posteriorly, the anterior lateral angles 

 broadly truncate, the truncate portion widely but slightly emar- 

 ginate, making the extreme anterior lateral angles of the 1st 

 segment rather prominent, the sides of the 1st and of the 2nd 

 segment at base laterally flattened ; the abdomen above convex, 

 the 2nd segment indistinctly medially longitudinally carinate ; the 

 3rd segment deeply depressed along the base, strongly transversely 

 incrassate before the well-marked anteapical series of foveae : the 

 apical area ample, the apical margin with 4 subequal large tri- 

 angular teeth, the medial two slightly advanced and closer to each 

 other than either is to the next tooth on the outside. 



The genus contains but one species with three well-marked 

 varieties, of which two are found within our limits. 



513. Stilbum cyanurum, Forst. (Chi-ysis) Nov. Spec. Ins. 1771, p. 89; 



Mocs. Man. Chrys. 1889, p. 190, pi. 2, tigs. 3, 4 & 16. (PI. I, fig. 6.) 



Chrysis amethystina, Fabr. 



2 st. Ent. (1775), p. 359 ; 

 Buyss. (Stilbum,) Jour. 

 Bomb. N. H. Soc. x (1896), 

 p. 478. 



Stilbum splendidum, Spinola, 

 Ins. Ly. i (1806), p. 9; 

 dtt Buyss. Jour. Bonw. N. 

 H. Soc. x (1896), p. 478, 

 pi. iii, figs. 9-12, pi. iv, 

 tigs. 1-4, & pi. v, fig. 8. 



True S. cyanurum, Forst. , 

 does not, so far as I know, 

 occur within our limits. 



Var. splendidum, Fabr. 

 . Metallic green, the 3rd 

 abdominal segment purple ; 

 the occiput, medial area of 

 mesonotum, and the 1st and 2nd abdominal segments more or 



Fig. 151. Stilbum ci/anurum, 

 var. splendidum , head and thorax, 



VOL. II. 



2p 



