INSECTA MADERENSIA. 543 



specimen which I have seen was captured by myself at the edges of the stream in 

 the Ribeii-a de Santa Luzia during, I believe, the winter of 18i9. 



Genus 185. XENOMMA, Woll (Ta^u. XIII. fig. 4.) 



Corpus parvum vel minutiim, elongatuni, lineare vel antice acuminatum : capite exserto ovato ; oculis 

 minutissimis demissis, supra marginem lateralem omnitio sitis : prothorace subquadrato ad 

 latera plus miuusve rotundato, antice et postice truncate : scutello vel magno scutiformi vel 

 minore transverso triangulari : elijtris valde abbreviatis, latera corporis amplectentibus, postice 

 praesertim ad angulum exteriorem sinuatis : alls obsoletis : abdomine marginato elongate, basin 

 versus plus minusve constricto, segmento ultimo retractili sed sat perspicuo (stylis analibus baud 

 exsertis). Antennm (XIII. 4«) ante oculorum marginem internum inserta?, capite prothoraceque 

 plerumque paulo longiores, robusts, apicem versus sensim incrassatoe, articulis tribus baseos 

 reliquis longioribus (primo leviter robusto), ultimo subacuminato-ovato. Labrum (XIII. 4 6) 

 amplum subquadrato-transversum valde pilosum, antice integrum et in medio leviter productum. 

 Mandibula (XIII. 4 c) magnse porrectje, apice angustse incurvae acutse obscurissime bifidse, intus 

 dente medio obscuro obtuso et membrana basilari instructse. Maxilla (XIII. 4 rf) biloba- 

 angustfe ; lobo externa apice pubescente : interno buic vix longiore, intus prEesertim ad apicem 

 pube longa dense ciliato (baud spinuloso). Palpi maxillares elongati, articulo primo minute, 

 secundo et tertio elongatis subiequalibus clavatis (illo subcurvato, boe paulo erassiore apice 

 truncate), ultimo subulate brevissimo : labiales (XIII. 4 e) e scapis ligulse connatis surgentes, 

 articulo primo elongate subcylindrico robusto, secundo paulo angustiore brevi, ultimo buic lon- 

 giore subulato tenuissime. Mentuin subtriangulare, apice truncate et leviter emarginate. Ligula 

 elengata linearis angustissima, ad apicem ipsum tenuiter et recte bifida ; paraglossis obsoletis. 

 Pedes lengiusculi : tibiis pubescentibus, ad apicem internum bicalcaratis : tarsis 5-articulatis ; 

 anticis articulis ultimo et penultimo medo inter se arete cennatis (sutura Eegre observanda), 

 mode (XIII. 4/) bene distinctis ; posticis articulo prime leviter elongate ; unguiculis elongatis. 



A f evo? mirabilis, et 6iJiiJi.a fades. (Typus — Xenomma planifrons.) 



The singular and truly indigenous insects on which the present genus is founded 

 are in some respects allied to 3£yrmedonia, or even to Oxijpoda, though at the 

 same time differing from them both in many essential particulars. In their 

 apterous bodies, in fact, and excessively diminutive, imperfectly constructed eyes, 

 which are placed altogether above the lateral edges of the head (itself moreover 

 being unusually ovate and elongated), as well as in then- largely developed and 

 porrected mandibles, and in the insertion of their antennae, which are remote from 

 the inner margin of the eyes, they recede from the whole of the Aleocharides with 

 which I am acquainted ; whilst, from Oxypoda in particular (with which in their 

 pentamerous feet* they coincide), their centrally-subacuminated upper lip, longer 

 and less spinulose inner maxillary lobe, in conjunction with their very narrow, 



* In the X. planifrons the two front tarsi have theii- five joints well-defined ; but in the formimrum 

 and Jiliforme the penultimate and terminal ones are very closely united together, so that it requires a high 

 microscopic power (since they are of precisely similar breadth) to discover the division between them. 

 Nevertheless, tliat it is to be detected, a very careful examination of each of the species has thoroughly 

 comdnced me. 



