36 
(Fig. 6, a ) is quite narrow; the teeth are simple, about as long as 
their basal width, the median one and a lateral pair about twice 
as long as the others; exterior to each lateral tooth is another 
tooth set a little lower down; the lateral row of setae are two in 
number, rarely three. 
The upper surface of the head shows on the median line an 
elongate spot and a dot in front of it; on each side of the inter¬ 
val between these are two minute dots, and back of them two more 
dots. The anterior lateral pair may be confluent, or the entire 
pattern may be more or less obscured. The body pattern is varia¬ 
ble to some extent; there are oblique lines and curves on the 
thorax above, transverse bars on the narrower abdominal seg¬ 
ments, narrowed or interrupted at middle, a broad complex patch 
on the posterior enlarged portion, usually containing a pale median 
area towards the posterior extremity, a row of small median spots 
on -the ventral segments, beginning with a larger one on the pos¬ 
terior side of the thoracic prolegs, and often one or two conspicu¬ 
ous blackish spots on the sides of the posterior enlargement. 
The blood gills are compound; the main stem of each of the 
three primary filaments appears to curve forward, and produces 
simple branches on its posterior side. 
Pupa .—The pupa is brownish testaceous. The respiratory fila¬ 
ment divides close to the base and the fork almost immediately 
Fig. 7. Simulium johannseni , pupa, three-quarters’ view. X 8%- 
again divides, forming four long filaments each side. On the dor¬ 
sum of the abdomen there are anteriorly three transverse series 
of strong dark-brown hooks recurved forwards, eight in each, four 
on a side, quite regularly spaced and not very close-set, with a 
broad median interval. These are near the posterior margins of 
segments 2, 3, and 4; those on 2 are smaller than the others. 
Back of these are four rows of smaller and lighter-colored poste¬ 
riorly recurved hooks, six or eight on a side, closely but irregularly 
set, with a lesser median interval. These are near the bases of 
segments 6, 7, 8, and 9. At the apex is a rather distant pair of 
short spines. Beneath, segments 4, 5, 6, and 7 each bear near the 
