288 Mr. Westwood on Diopsis, 



Athericera (containing the Syrphidce), of which " le Su^oir se compose de 

 quatre pieces, et non de deux comme dans tons les autres Atheric^res-" the 

 two maxiiloe being clearly developed* and very acute, and the palpi longer 

 than the labrum, compressed, and broader towards the apex than at the base. 

 The ABDOMEN exhibits another peculiarity, all the specimens which I have 

 examined having the four basal joints soldered together, without any distinct 

 articulation, on the upper side of the abdomen : this is the case even in D. sig- 

 nata andfasciata, in which the situation of the articulations is indicated by a 

 black slender line. This structure is represented in Linnseus's original figure ; 

 but Dalman, who drew the figures accompanying his memoir, has represented 

 the articulations of the basal segments in all his species. 



DIOPSIS. Lhm. et Auctt. 



Characteres Generis. 



Corpus parvum, elongatum, longitudine vix dimidium uncii tequans. Caput 

 parvum, suprk subtrigonum, facie antica perpendiculari, subconica, sub- 

 ttis truncata, mutica, vel utrinque unispinosa, latere supero vel vertice 

 in medio ocellifero, et utrinque in cornu longissimum cylindricum plus mi- 

 nfisve gracile subascendens, ad apicem oculiferum, et pauUo ante apicem 

 antenniferum divergens producto. Hsec cornua in medio vel pone medium 

 seta unica alteraque ad apicem supra oculos armantur. Antennce minimse, 

 compressse, 3-articulatae articulo Imo minimo transverso, 2do majori 

 cyathiformi, 3tio suborbiculato supra ferfe ad apicem, seta (basi articu- 

 lata,) simplici longa. Os in cavitate capitis infera retractile. Pro- 

 boscis magna, membranacea, geniculata. Portio basalis magna, rotun- 

 data, et pro receptione partium oris internarum concava (an labri vera 

 pars analogica?). Labrum (dimidii labii longitudine) acuminatum, crus- 

 taceum, et pro receptione linguae subtus carinatum. Lingua labro paullo 

 brevior, gracilis, compressa. Maxillce distinctse, lingua breviores, gra- 

 ciles, acutissimse. Palpi labii fer^ longitudine, ad basin arcuati (articu- 

 lati ?), compressi, versus apicem dilatati, pilosi. Labium magnum, stipite 



* Since this account was written, Mr. Curtis has illustrated the genus Borbortis in his "British 

 Entomology," which he describes as possessing " maxillse very small and linear." {Brit. Ent. 469.) 



