34'2 GNATS OR MOSQUITOES— CHAPTER XIII 



< he exception of a broad basal white band on the fourth joint of 

 the hind legs. Thorax sooty, clothed on the mesonotum and 

 scutellum, with short falciform, golden scales with numerous long 

 stiff black bristles on their margins. Abdomen, deep amethystine 

 purple, with triangular apical golden spots on each segment, and 

 some yellow scales and hairs along the hind border of the first ; 

 ventrally, the segments show triangular golden apical markings. 



There can be little doubt that it was upon this species tliat Arribiil- 

 zaga founded his new genus, as it agrees entirely with his description, 

 given below, while specimens, sent to Mr. Theobald by Dr. Lutz, and 

 which correspond to Walker's type of C. discrucians, though believed by 

 the latter naturalist to be Arribalzaga's species, were at once seen to 

 fail to correspond with Arribalzaga's description and figure, and it is 

 obviously unlikely that the discrepancies can be due to careless draw- 

 ing. This difficulty is now set at rest by a specimen I have just received 

 from Dr. Lutz, labelled " Janthinosoma, sp. n.," and which was at once 

 recognised by Mr. Theobald as the missing species. 



The head and appendages almost black, tlie vertex and nape clothed 

 with erect forked, and short falciform golden scales. The pleuriE and 

 coxae show extensive areas of golden scales and the lower surfaces of the 

 femora, and the base also above of those of the hind legs, are bright 

 golden, the apices of the femora showing also a barely noticeable yeUow 

 knee-spot. 



This species can be easily distinguished from any other of the genus 

 by the single band on the hind tarsi. 



Original description : — 



" ( 2 and $). — Blackish, somewhat steely. Head clothed behind and 

 below with pale golden scales ; antemise fuscous ; proboscis dark steely ; 

 palpi of the (? much longer than the proboscis, with an apical brush ; 

 those of the $ dark steely with the last joint large and oblong. Thorax 

 with dark fawn-coloured scales above, with greyish -golden scales below 

 and on either side. Wings limpid with fuscous scales, which are densely 

 arranged in front and more sparsely behind ; first sub-margmal cell longer 

 and narrower than the second posterior, their stems neai-ly equal, but 

 while that of the first sub-marginal is barely half the length of the cell, 

 the stem of the second posterior is quite as long as its cell. Legs dark 

 steely, but with the femora broadly pale yellowish at the base ; hind tarsi 

 with the base of the fourth joint adorned with a pale yellow band. 

 Abdomen steel-coloured above, the first segment with broad silvery 

 fringes, the remainder not fringed but golden on either side ; the venter 

 with pale golden arcs. Length. — 6 mm. 



''Habitat. — South America (AValker) ; Argeutma (Arribalzaga)." 



6. JANTHINOSOMA OBLITA, Arribdlzaga (" L. A." p. 54). 



Wings unspotted ; tarsi without obvious bands ; thorax un- 

 adorned, dark grey ; abdomen undescribed, but presumably 

 unhanded. Nothing resembling this has come to hand. 



