272 INSECTA MADERENSIA. 



picescent (especially in the Porto Santan specimens), and almost free from scales; the former 

 distant at their insertion, and with their last two joints distinctly and suddenly thickened,-^ 

 forniins: a biarticulated club. 



The deep black siu'face of the present anomalous little Tt'mns (which has its 

 head and prothorax, especially the latter, incrusted with sno\^y-white scales), in 

 connection with its comparatively quadrate (though very convex) form, would 

 even of themselves at once distinguish it from the remainder of the genus here 

 described. Its structural details hoAvever are far more important, and altogether 

 remove it from the other Madeiran members of the group, — its antennae not only 

 l)eing distant at their base (of very rare occurrence amongst the Ptiiii, though one 

 of the essential characteristics of Hedobia, — with which nevertheless in other 

 respects it does not coincide), but having likewise their last ^?t'o joints so distinctly 

 and suddenly thickened as to constitute a tolerably well-defined Inarticulated club. 

 It displays moreover a very remarkable feature (which observation however in situ 

 can alone appreciate) in the exceedingly fragile nature of its Hmbs, Avhich are so 

 delicate and easily removed, that it was with the utmost difficulty that I could 

 procure so much as a single perfect specimen out of a very large number wliich I 

 have, on various occasions, captured during my researches in these islands. And 

 I would lay particular stress on this peculiarity, since the limbs of the Ptini are 

 generally not only remarkably robust, but so fii-mly attached to the liody that it 

 requires consideralde force to disengage them ; — and the present species may con- 

 sequently be regarded as entirely aberrant from the normal representatives of the 

 genus. I have not hitherto detected it in Madeira proper ; but it is abundant in 

 Porto Santo and on the Dezerta Grande (esjiecially the former), where it resides, I 

 believe exclusively, amongst the dense masses of lichen which choke up the 

 fissures and besprinkle the surfaces of the exposed weather-beaten rocks. It 

 occurs during the spring and early siunmer months, in company Avith the 

 P. nodulus and (ilboplctns, Tarphius Loicei, Xenostrongylus hi^trio, and the 

 numerous other insects of similar propensities. 



Genus 94. MEZIUM. 

 (Leach) Curtis, Brit. Ent. v. 232 (1828). 



Corpus parvum, durum : capite deflexo, sub prothoracf abscondito : protlwrace squamoso gibboso, mox 

 ante basin valde dilatato sed ad basin ipsam subito constricto : scutello baud observando . elytris 

 politissiiuis compresso-ovatis subconnatis : alls obsoletis. Antenna approximatae setuloso-squa- 

 mosic filiforuics, articnlo primo magno robusto intus producto, secundo paulo breviore graciliorc, 

 reliquis (ultimo ovato oblique subtruncato excejjto) suba>qualibus. Labrum corneum, antice 

 pilosum valde emarginatum. MandibuUe et maxilla fere ut iu Ptiuo. Pulpi subclavati ; maxil- 

 lares articulo ])rimo longiusculo subgracili ilcxuoso, secundo et tertio crassioribus subwqualibus, 

 ultimo elougato-ovato robusto ; labiales articulo primo longiusculo subgracili flexuoso, secundo 

 crassiore, ultimo ovato robusto. Mentum corneum triangulare pilosum. Ligula elongata sub- 



