dorsum, figure 133; the sides are black, with a brown mark ex- 
tending back from the caudal margin of the eye to the caudal 
margin of the head as shown in the figure; the venter is black, 
except the ventral mouth-parts, which are brown; the labrum is 
black, with sete arranged as in figure 139; its cephalic pair of 
sete are saber-like and are directed toward the median line, their 
tips almost meeting; the other sete: are normal; the front margin 
is clothed with a dense fringe of hairs; the frons has the markings 
and distribution of setz, shown in figure 147. 
The Thorax—tThe thorax is marked on the dorsum, as in 
figure 133; the prothorax has a depressed crescentic mark of 
brown across the dorsum and extending down the sides ; the meso- 
thorax is armed dorsally with four narrowly separated chitinous 
plates, which are without markings, but are armed with long sete, 
figure 133 ; on each side of the body there is a somewhat triangular 
plate; the metathorax is armed above with four smaller dorsal 
plates and a single plate on each side of the body, figure 133; on 
the sides the chitin of the dorsum of the prothorax extends to the 
base of the front legs; on the outside of each mesothoracic coxa 
there is a triangular piece of heavy chitin which bears a tuft of 
long, black sete on its front and on its ventral corners; the meta- 
thorax bears similar chitinous pieces, each of which has a single 
line of long, black setee around its cephalic corner and a line of 
similar sete, extending from a point on its cephalic margin well 
above its ventral corner to a point on its venter considerably below 
the limits of the chitinous triangle; the venter of the thoracic seg- 
ments is without heavy chitin. The legs, figures 134 and 146, are 
BRACHYCENTRUS NIGRISOMA. 
133. Larva. Head and thorax. 141. Larva. Mandible. 
134. Larva. Front leg. 142. Larva in case. Natural posi- 
135. Pupa. Chitinous plates of left tion, cephalic view. 
side of abdomen. 143. Adult. Male genitalia, caudal 
136. Larva. Distribution of giills. view. 
137. Pupa. Detail of group of 144. Larva in case. Dorsal view. 
hooks, 2nd __ series, 145. Larva. Lower mouthparts. 
segment 5. 146. Larva. Middle leg. 
138. Larva. Drag-hook. 147. Larva. Frons. 
139. Larva. Labrum. 148. Pupal case. a) caudal end of 
140. Larva. Part of comb of 2nd case. b) caudal sieve. 
leg. c) cephalic sieve. 
85 
