ALT7KNUS. 25 



(fig. 8^) magna, segmento hasilari (fig. 8 ^) crasso, subpenta- 



gono, apice obtiiso, antice iitrinque valde excavate (palpis in 



emarginatione inscrtis). 

 Oculi ovati. 

 Thorax transversus, apice rotuiidatus, lateribiis sinuatis, antrorsum 



valde declivibiis. 

 Scutelimn (fig. 8?') semiovatum, apice subacxitiim. 

 Elytra oblonga, apice rotiuidata. 



Pedes robusti, mediocres, femoribiis siibincrassatis, tarsis latis. 

 Corpus oblongum, subeonvexum, dorso subdepressum. (Type, 



Alurnus marginatus, Latr.) 



This genus (all the species of which are South American) contains 

 the largest and most beautiful insects in the whole family ; it may 

 at once be distinguished from the rest of the genera by the striking 

 and singular shape of the basilar segment of the ligiila ; this is 

 much enlarged, and forms the principal portion of the whole labium ; 

 when viewed from below, it entirely conceals the apical segment. 

 Ohvier, who has given in his great work an erroneous figure and 

 description of this organ, has evidently made his dissection from an 

 insect belonging to a totally different genus. 



1. Alurnus marginatus, Latr. B.M. 



Lair. li^gne Anhn. Ins. Texte, p. 503. pi. 71. fig. 3. 

 Guer. Iter. Zool. 1840, p. 330. 



A. supra nigro-viridis ; capite, thoracis lateribus elytrorumque limbo 

 fuMs ; antennis scutelloque nigris ; infra ful\T.is ; femorum apice, 

 tibiis tarsisque nigris. 



Long. 14-16 hn. 



Var. A. Elytris fascia transversa plus mrnusve interrupta, fulva, 

 Hab. Brazil. 



This is the most common insect in the genus, and is sent over to 

 this country in almost every Brazilian collection ; the variety is also 

 very common. 



2. Alurnus thoracicus, Perty. B.M. 



Perty, Del. Anhn. uirfic. p. 99. tab. 20. fig. 2. 

 Guer. Per. Zool. 1840, p. 330. 



A. niger ; macula vcrticali, thorace lateribus femoiibusque sangui- 



neis. 

 Long. 13 lin. 



Var. A. Thorace sanguinco, antice posticeque nigro-marginato. 



Var. B. Supra sanguineus, elytris macula humerali chmidio(|ue pos- 

 teriori chalybeis. 



