the Hydroptilidce. 141 
Female very similar, but Avitli the markings of the wings 
less distinct. 
Leno;th with closed wino;s ^24 mm. 
Hah. — The Sandy Brookj near Hanging Bridge, Ash- 
bourne, Derbyshire. June. Does Hydroptila hrunnei- 
cornis, Pict. belong here ? The colour of the antennas is 
similar, and the number of spurs is stated to be 0, 3, 4, by 
Dr. Hagen in a letter from him to Mr. M'Lachlan, he 
having examined types. 
Genus Orthotrichia, nov. gen. 
Neuration, PI. II. 4 ^ , 4 a $ . 
Hydroptila (part), M'Lachlan, 1865. 
Derivation. — (Gr.) Ortlio-tlirix, with hair upstanding 
or on end. 
Imago. AntennfB of the male about three-quarters as 
long as the wings, filiform, the joints subcylindrical with 
closely adpressed hairs, the basal joint rather larger than 
the others: in repose divergent and ascending. Ocelli 
absent. Maxillary palpi filiform, with moderate slightly 
spreading hair, five-jointed; the first two joints very short, 
equal ; the next two joints subequal to one another ; the 
fifth joint a little the longest. Labial palpi filiform, Avith 
the joints successively increasing slightly in length. Head 
and prothorax with dense shaggy hair. Wings linear 
lanceolate, acuminate, with very long fringes; the anterior 
scabrous, without an appendage to the post-costa, discoidal 
cell open, the ramus discoidalis forked, with both prongs 
forked ; the superior branch of the ramus thyrifer forked, 
the anterior prong forked, the posterior prong simple ; thus 
there are two forks before the apex and one behind it ; the 
posterior wings with adpressed hair, the costa shallowly 
concave in its second third, and with one transverse 
veinlet; the ramus discoidalis forked, with the anterior 
prong simple, the posterior prong forked ; the ramus sub- 
discoidalis forked with simple prongs ; thus there is one 
fork before the apex. Legs of moderate length, the pos- 
terior tibiffi and the base of the tarsus strongly fringed 
externally; anterior tibia spurless, intermediate Avith three, 
posterior with four spurs. Abdomen with small appendices 
and setiform penis, the antepenultimate segment in the 
male with a slender ventral lobe ; after death the penis is 
usually extruded. 
The species inhabit warm rivers and lakes in England, 
