130 Mr, R. M‘Lachlan’s Monograph of the 
to identify it with any described species. It varies in the number 
of the pale spots and very slightly in size ; the only British species 
agreeing with it in this respect is H. ophthalmica. It may possibly 
be the H. guttata of Pictet. 
b. Eyes (of the male only?) large. Vertex nearly quadrate, 
slightly longer than broad. 
6. Hydropsyche ophthalmica, Rambur. 
Hydropsyche opthalmica, Ramb. Hist. Nat. Névrop. p. 505, 2 
(1842); M‘Lach. Ent. Ann. 1864, p. 152. 
Antenne whitish, with very distinct oblique black lines. Head 
thickly clothed with whitish pubescence. Palpi whitish-grey. 
Mesothorax blackish. Anterior wings whitish, reticulated with 
grey, with blackish spots towards the dorsal margin; apical 
margin grey and whitish alternately. Posterior wings pale whitish- 
subhyaline. Legs pale whitish-ochreous; the apex of the ter- 
minal joint of the anterior and intermediate tarsi blackish. Ab- 
domen brownish above, ochreous beneath. In the male the 
superior horny lobe is very short and brown, the membranous 
parts beneath it yellow; app. inf. greyish-white, the basal joint 
much dilated in its apical portion and externally marked with 
black, apical joint much incurved and scarcely dilated at the tip; 
penis testaceous, much swollen below the apex, which is darker 
than the other parts. 
Expanse of fore-wings 84—9 lines. 
Occurs along the Thames about Kingston, Kew, &c. in autumn. 
The peculiar structure of the eyes will readily distinguish this 
species from all others. 
I am inclined to think that the male only possesses the enlarged 
eyes. his insect is very common in August along the Seine at 
Paris, frequenting the river-walls and the interiors of the baths, 
as I observed in August, 1864. The only female Hydropsyche 
that I saw there had eyes of the ordinary size, and, as I found the 
male of no other species of this genus, I think it may pertain to 
ophthalmica. 
Genus TrinopeEs, Leach. 
Antennz moderately stout, shorter than the wings, obsoletely 
dentate internally ; basal joint short, not much thicker than the 
others. Head convex above, hairy. Ocelli absent. Maxillary 
palpi long and thin; basal joint short; second longer; third as 
long as the two first united; fourth as long as the second; fifth 
