Staplnjiinidcc of the Amazon Valley. 143 



species are amongst the most brilliant of natural objects. 

 Ivraatz has remarked that the s])ecies fall into three dis- 

 tinct groups, adding, that it will be well to leave them 

 together in one genus till more species are known. The 

 species I here describe as T. mutator adds yet another 

 form to those previously included under this generic name. 

 It is well to add, to prevent misconception, that though 

 the dilated terminal joint of the labial palpi is given as one 

 of the most important characters of the genus, S. venustus 

 and violaceiis have that joint quite simple, and are allied 

 to the Pliilonthus j)i'Gtlosus ^ Er., in this respect. 



1. Trifjonopselaphus opacipennis, n. sp. Capite tho- 

 raceque viridibus, nitidis ; elytris obscure jenescentibus, 

 opacis ; abdomine opaco, nigro, ajjice rufo-testaceo ; anten- 

 nis pedibusque nigris, illis articulo idtimo ferrugineo. 

 Long. corp. 9 lin. 



Antennffi the length of the head and half the thorax, not 

 thickened towards the extremity, black, AA'ith the 10th joint 

 pitchy and the 1 1th dull yellowish ; 3rd joint considerably 

 longer than the 2nd, quite twice as long as the 4th ; from 

 the 4th to the 10th each a little shorter than its predeces- 

 sor; 10th joint about as long as broad, the others longer 

 than broad; 11th joint about as long as the 9th, its ex- 

 tremity rounded, but pointed on one side. Pal[)i pitchy ; 

 mandibles black. Head scarcely as broad as the thorax, 

 rather quadrate, above shining green, with large, coarse 

 punctures irregulai'ly scattered, but leaving a rather broad 

 irregular space, extending from the labrum to the neck, 

 free ; below black and dull. Thorax a little narrower 

 than the elytra, rather longer than broad, very slightly 

 nan-owed behind, with the sides but little sinuate on the 

 upper side, with two lines of about eight punctures, with 

 a rather broad space between them, and besides these with 

 about twenty other })unctures on each side near the front 

 part and the outsides ; it is of a shining, bluish-green 

 colour; the margins below black and provided with a 

 stigmatic membrane. Scutellum large, black, dull, very 

 obsoletely and sparingly punctured. Elytra about as long 

 as the thorax, of a dull black colour with a slight metallic 

 tint, with a very peculiar sculpture consisting of large 

 shallow punctures, placed at a good distance from one 

 another, and Avith faint, irregular, wandering lines between 

 them. The hind body is narrowed towards the extremitv ; 



