250 Timehri. 
tural and Commercial Society of British Guiana, very kindly allowed me to 
examine the specimens under his charge, viz., four S. Amazonicum and two 
Simulium of the new species. 
_In view of the fact that the early stages of the metamorphosis (viz., the 
larva and the pupa) are passed in swiftly running well aérated streams it is 
obvious that these flies are only met with well up in the interior and are never 
seen along the flat mud-formed coast lands where the only waterways are 
sluggishly moving streams. The well known sandflies of these coast lands 
belong to the family Chironomide (Genera Culicoides and Ceratopogon). 
The Simulide are small obese flies usually of dark or subdued colour. They 
possess a very humped back, short legs and broad wings. They generally 
occur on or near waterways. No noise, hum or buzz announces their arrival, 
which is silent ; they feed on vegetable juices but the female attacks men and 
animals viciously and readily sucks blood. They swarm more particularly 
about sunset but will attack during the whole day. 
Simulium Amazonicum (Goeldi). 
This Simulium has been described by Goeldi (10) in 1905 but as the original 
description is not of ready access to all a short condensed summary is added 
below. 
Imago, female. Length 1.95—2.10 mm. Length of antenna 0.40 mm. 
Length of thorax 0.95 mm. Length of wing 1.15 mm. Depth of wing 0.90 
mm. The whole insect is of a blackish colour but in special lights and looked 
at obliquely shows beautiful iridescent and interference colours. The antenna 
consists of ten joints of which the basal two are the largest and the apical 
is conical with a delicate bristle. It is of a general brown colour rather lighter 
at the apex. The head is united to the thorax by a short neck and is com- 
pressed dorsoventrally. The two large compound eyes are separated and 
composed of facets of two sizes, those of the upper part being the larger. 
The proboscis and mouth parts are of a light brown colour and in a general 
way resemble the Culicide proboscis being however much shorter and stouter. 
The proboscis is composed of a paired fleshy labium completed by a labrum 
with which is incorporated a grooved epipharynx. The labrum carries a 
pair of sharp, hooked and simple teeth at the end. The stylets include a single 
hypopharynx carrying a central duct, with paired mandibles and maxille. 
The mandibles possess a row of small sharp teeth while the maxille are 
furnished with fewer but larger teeth curving backwards. The maxillary palps 
are large and long and consist of four segments each longer than the proximal, 
the distal segment being ornamented with numerous closely set rings. 
The frons and vertex are of a bluish tinge, have no ocelli and carry a few 
irregular fine bristles. 
(10,) Memorias do Museu Goeldi Vol, IV. Os Mosquitos no Para pp, 138, 139. 
