110 INSECTA MADERENSIA. 



liindor pvothoracic angles being scarcely at all produced*. It is an abundant insect 

 througliout Madeira, l)elo\v the altitude of al)Out 3000 feet, during the summer 

 and autumnal months, — occui'ring principally at the roots of grass, and beneath 

 leaves and other decajdng vegetable substances. In the vicinity of Funchal, and 

 also at Santa Anna, I have observed it at times in great profusion. 



Genus 41. PTENIDIUM. 



Erichson, JVo^ der Lis. Deutsch. iii. .Si (1848). 



Corpvis minutissimum, ovale, convexiusculum, nitidissimuru, subglabrum : prothorace lateribus rotun- 

 datis, antice et postice subfequaliter angustato, angulis posticis plus minusve rotundatis : ebjtris 

 apice iiitegris subacuminatis : mesosterno vix carinato, scutello magno : abdomine ex scgmentis 

 ventralibus septem composito : alis amplissimis lanceolatis, pilis longissimis instructis. Instru- 

 menta cibaria fere ut in Acratrichi. Pedes valde cursorii, graciles : coxis posticis simplicibus 

 distantibus : tarsis 3-articulatis, articulo ultimo elongate. 



The present group may be known from the previous one by the more oval, con- 

 vex, and polished bodies of the minute insects which compose it, — the ehi;ra of 

 which cover the whole of their abdomen, instead of being (as in Acndrichis) 

 aln'uptly truncated behind. Theii' upper siu'face, moreover, is almost entirely free 

 from punctures and pubescence, and theii' prothorax (instead of being dilated) is 

 constricted at its base, Tvith the posterior angles more or less rounded and obtuse. 

 In their habits, the species are similar to the members of the last genus. 



88. Ptenidium apicale. 

 P. oblongo-ovale convexum subglabnim nigrum nitidissimum remote punctatum, prothoracis angulis 



posticis lateribusquc rotundatis, clytris apicem versus late flavescentibus, antcnuis pedibusque 



pallido-testaceis. 

 Long. Corp. lin. |. 



Ptilium apicale, Stunii, in Utt. 



Trichopteryx apicalis, Grillm. in Sturm, Deutsch. Fna, xvii. 85 (1845). 



Ptenidium apicale, Erich. Nat. der Ins. Deutsch. iii. 3G (1848). 



Habitat Maderam, ad radices graminum, vel sub lapidibus foliisque arborum marcidis toto anno 

 vulgaris : ctiam in ins. Deserta Grandi occui'rit, qua Maio exeunte, a.d. 1850 pauca specimina 

 cepi. 



* Tlie present Aci-atrichis varies the eightli of a line iu length, and a little in outline, according to the 

 altitude and cLrcimistauces imder which it is found, but it retains the same characters of coloiu-, scul])- 

 ture, and pubescence throughout, — as 1 have been able to ascertain from the examination of a very large 

 series of specimens collected from .ill parts of the island. I should mention however that it was separated 

 into three species by ^l. ^rotj^chulsky, two of them being considered as new. for which he proposed the 

 names of nigricornis and ovatula; whilst the third (dcj)eudiug on a single indixidual, without a head) he 

 identified with the minutissima of Linna>us. In my opinion, however, they are all referable to one ; and 

 T am inclined to think that the common A. pumila la the species to which they must be assigned. 



