252 Timehri. 
The above description of the British Guiana variety of ‘‘ Pium fly’’ cor- 
responds closely with the description of the amazonicum “ Pium fly ” given by 
Goeldi. 
Goeldi describes a characteristic pattern on the thorax ‘“‘ made up of l. A 
median straight band; 2. Two curved lines in shape of a half moon combining 
with the middle one to form a T turned to the front (one could speak of five 
longitudinal thoracic lines).”” The description though not identically similar 
to figure 2 yet shows a very close resemblance. 
Again in the leg markings certain differences may be noted. 
In the first pair of legs Goeldi describes the tibia as being fuliginous, in the 
second pair the tarsus is light coloured as well as the rest of the leg. 
The differences are small and insufficient to create a separate species. 
This Simulium amazonicum approximates somewhat to Simulium quadri- 
vittatum (11), a species from Cuba but may be distinguished by the thoracic 
ornamentation and the leg markings. 
Specimens of this Simulium have been sent to the British Museum, to the 
London and Liverpool Schools of Tropical Medicine. 
Simulium Guianense. n. sp. 
Imago, female. This fly was found by Melville on the Essequebo river and 
its higher branches in British Guiana and is known as the “ Itanimi fly,” this 
being distinguished by the Aboriginal Indian from the * Pium fly.” 
It is larger than Simulium amazonicum and is of a light silvery grey colour. 
The length of the whole fly is 2.35—3.10 millimetres, the length of antenna 
is 0.55 m.m., the length of thorax is 1.25 m.m., the breadth 1.10 m.m. The 
length of wing is 1.35 m.m., the breadth 1.10 m.m. 
The general colour is light grey with a silvery shimmer. No interference 
colours or metallic iridescence were noted except occasionally on the wings. 
The antenna is composed of ten joints all of a yellowish colour and covered 
with short white hairs. The distal joints are brownish. The compound eyes 
are deep black and well separated and in this fly also the upper facets are larger 
than thelower. The proboscis is of yellowish brown colour and is composed of 
the same elements as that of S. Amazonicum. The labrum has at its distal 
extremity six well marked hooked teeth, three on each side. 
The Maxilliary palps are yellowish brown of four joints and covered with 
many hairs. The first has an oval sac like a sense organ. The second to the 
fourth segments have numerous pitted surface markings giving the impression 
of rings. 
(11,) Felt, Aquatic Insects in New York State, 1903, p. 354. 
