48 Mr. H. W. Bates on the Longicorn Coleoptera 



surface clothed with minute silky-green scales, and having a 

 well-marked sutural stria with regular rows of black bristles, 

 each proceeding from a puncture. Sides of breast rich golden 

 green ; sternum clothed with hoary tomentum ; abdomen red- 

 dish testaceous, clothed (especially towards the base) with hoary 

 pile. Legs black; thighs beneath hoary. 



S Apical abdominal segment much longer than the medial 

 segments ; ventral plate obtuse at the tip ; dorsal plate square, 

 with the angles each produced into a stout tooth. 



? Apical abdominal segment of the same relative length as in 

 the (5", but the ventral plate more convex; dorsal plate narrowed 

 towards the tip, and terminating m two stout teeth. 



One pair, taken in copula on a dead branch, at Obydos, on the 

 Guiana side of the Lower Amazons. The insect has a deceptive 

 resemblance to species of the Cerambycideous genus Chryso- 

 2)rasis, found in the same localities. 



2. Prohatius humeralis, Perty. 



Acanthocinus humeralis, Pertv, Delectus Anirn. Art. Itin. Spix & Martius, 

 p. 91, pi. 18. fig. 8. 



P. oblongus, fusco-niger, sericeus : thoracis vitta centrali, scutello, 

 macula elytrorum utrinque humei'um circumdante lineaque abbre- 

 viata marginali aurantiacis. Long. 4^ lin. (S $ . 



The apical abdominal segment is of nearly the same shape 

 in both sexes as in P. Chryseis ; but the ventral plate in the $ is 

 briefly notched at the apex. 



This species has a wide range. I have specimens before me 

 from Rio Janeiro, the Upper Amazons, and Cayenne. It is also 

 found in Mexico, but exists there under the form of a well- 

 marked local variety or race, the P. mexicanus of Thomson (Classif. 

 des Ceramb. p. 17). This differs from the South-American form 

 by the orange-coloured marginal streak extending to the tip of 

 the elytra, instead of halting halfway, and by the thoracic vitta 

 extending over the crown of the head. 



3. Probatius partitus, White. 



P. ellipticus : capite, thorace (brunneo indistincte bivittato) articulo- 

 que basali antennarum testaceo-ochraceis : elytris postice valde 

 attenuatis, nigris, nitidis, basi obscure testaceis, maculis minutis 

 griseis in fasciis undulatis tribus dispositis, nigro setosis, striato- 

 punctatis, postice unicarinatis. Long. 4-4f lin. 



The apical abdominal segment is of a similar form in both 

 sexes to that of P. Chryseis. The antennae, excepting the pale 

 basal joint, are black, with the bases of the joints whitish. The 

 thoracic spines are thick, conical, and obtuse. The apical spines 



