154 Mr. R. M‘Lachlan’s Monograph of the 
The following is a tabular arrangement of the British genera :— 
Spurs 3-4-4 . . . . . . «© Rhyacophila.- 
Spurs 2-4-4. . . . . « « Agapetus and Glossosoma. 
Spurs 2-2-4 So eure elt a vor AREnCE Oe 
Spurs 0-4-4 (3), 1-4-4 (¢) .  . Chimarra. 
Genus Ruyacopuita, Pictet. 
Antenne rather shorter than the wings ; basal joint thick, shorter 
than the head. Head nearly quadrate. Ocelli present. Max- 
illary palpi with the first two joints very short and nearly globular, 
the others cylindrical and nearly equal, the third slightly the 
longest. Labial palpi with two broad and dilated basal joints and 
a somewhat longer and thinner cylindrical terminal joint. Meso- 
thorax short and robust. Anterior wings narrow at the base, 
dilated towards the elliptical apex; costal margin somewhat 
rounded ; hairy clothing very slight; neuration strong and dis- 
tinct; an oblique transverse vein uniting the costa and subcosta 
near the middle; radius slightly bent before its termination ; 
discoidal cell open (in all the wings); a straight transverse vein 
uniting the lower branch of the ramus disccidalis to the upper 
branch of the ramus thyrifer, and an oblique one, placed more 
posteriorly, uniting the two branches of the ramus _ thyrifer. 
Posterior wings similar in form to the anterior, but somewhat 
shorter. Legs long, anterior tibiae with one median and 
two long equal apical spurs; intermediate and_ posterior 
tibia each with two pairs of long and nearly equal spurs.* 
Abdomen slender in the male, robust in the female. In the 
antepenultimate ventral segment in the male there is a small 
pointed tubercle; the upper margin of the last abdominal seg- 
ment is produced into a lobe varying according to the species, 
sometimes very long; app. sup. small, lying under this Jobe and 
often concealed by it; app. inf. very long and bisarticulate ;_ penis 
long, furnished with two valves and with long needle-shaped 
sheaths on either side. In the female the extremity of the ab- 
domen is obtuse; at the apex are seen two somewhat hairy valves 
fitting round a short thick tubular piece, from the interior of which 
the small ovipositor can be exserted at will. 
Larva inhabiting swiftly-running streams ; elongate, flattened ; 
head and first thoracic segment small and corneous (see Pl. 11. 
fig. 16); mandibles simple; two last thoracic segments and the 
abdomen soft; legs short and thick ; abdominal segments broadly | 
transverse, each (and also the two last thoracic segments) provided 
with a large tuft of respiratory filaments on each side; anal 
crotchets very long and claw-shaped. 
