INSECTA MADERENSIA. 597 



for their identification. The abdomen and penultimate tarsal joint of the various 

 representatives aff'ord an easy clue to their sectional distribution, — the former 

 being either margined or simple ; whUst the latter is in some cases bUobed, and 

 in others entke. They are insects which reside principally in damp sj)ots, — 

 running with the utmost agility (especially during the hot sunshine), and being 

 often exceedingly numerous under stones and upon wet mud at the edges of 

 ponds and streams. They are widely disseminated over the world, more than 

 100 species being described by Erichson, — and upwards of 90 having been 

 recorded as Em-opean. 



§ I. Abdomen marginatum : tarsi articulo qiwrto simplice. 



467. Stenus giittula, 

 S. niger gracilis, crebre et rugose pinictatus, parce subsenescenti-argenteo-pubescens, prothorace sub- 

 fusiformi-angusto subinjequali, elytro singulo macula media fulvo-testace^ ornato, palpis pedi- 

 busque testaceis, femoribus ad apicem late nigris. 

 Mas, abdominis segmentis quinto et sexto subtus obsolete sinuatis, illo vix impresso sed in media 



ipsd parte impunctato et utrinque pilis sat longis introrsum vergentibus ciliato. 

 Fcem., abdominis segmento sexto subtus in medio leviter producto rotundato. 

 Variat palpis et tibiis, praesertim apicem versus, obscurioribus. 

 Long. Corp. lin. 2. 



Stenus guttula, Wa^.Qcerm. Mag. vr. 225 {1821). 



Kirlii, Curtis, Brit. Ent. iv. 164. pi. 164 (1827). 



guttula, Ericb. Gen. et Spec. Staph. 691 (1839). 



, Heer, Fna Col. Helv. i. 214 (1841). 



Habitat per margines rivulorum Maderse, inter lapillos latitans, ubique vulgar 



S. black, slender, nearly opake, and sparingly clothed (more densely so on the abdomen) with a short 

 yellowish-, or ceneous-silvery pubescence. Head and protlwrax closely and roughly punctured ; 

 the former deeply excavated between the eyes, and with a narrow central keel behind, — and with 

 the joa^z either entirely pale testaceous, or else with the extreme apex of the third joint, and the 

 greater portion of the fourth infuscated ; the latter narrow and somewhat fusiform (being widest 

 about the middle), and rather uneven. Ehjtra as closely and coarsely punctured as the head 

 and prothorax, and with a large rounded spot immediately within the middle of each bright fulvo- 

 testaceous. Antenna with the intermediate joints more or less piceous. Legs testaceous, — with 

 the cox(E entirely, and the femora at their apex broadly, black (and occasionally with the tibise, 

 especially towards their extremities, and the tarsi infuscated or picescent). 

 Male, with the fifth and sixth segments of the abdomen beneath most obsoletely sinuated (or sub- 

 emarginate) ; the former scarcely impressed, but with a small central apical portion unpunctured, 



•IS. 



hoc genere Ugula levissime mento afSsa est, quo fit, ut agone mortis vi anteperistaltica oesophagus ciiiii 

 ligula, paraglossis palpisque labialibus prolabitur et promuscidis porrectse speeiemprse se ferat." 



