144 Mr. R. M‘Lachlan’s Monograph of the 
circle in the middle. Pronotum small and short, also fawn- 
coloured. Meso- and meta-nota and abdomen fawn-coloured, 
tinged with rose ; the abdominal segments marked with longitu- 
dinal sinuose impressions ; the last segment with a short base and 
two long pedicels terminated by simple hooks. Feet fawn-coloured. 
(Pictet.) 
A widely spread but not common insect, frequenting the neigh- 
bourhood of streams in summer and autumn, 
Genus Potycentroprvus, Curtis. 
Antenne stout, not so long as the wings; basal joint rather 
thicker and longer than the others. Head hairy. Ocelli absent. 
Maxillary palpi long; the two basal joints short; the third long ; 
the fourth about half the length of the third; the fifth nearly as 
long as the others united. Mesothorax robust. Anterior wings 
rather short, narrower at the base, dilated and obliquely rounded 
at the apex; hairy clothing short and dense; the neuration 
almost entirely similar to Plectrocnemia. Posterior wings folded, 
shorter and broader than the anterior, the costal margin slightly 
concave ; anal portion well developed ; fringes short ; discoidal 
cell closed or open; forks 1, 2 and 5 present, or 2 and 5 only. 
Legs moderately long; intermediate tibia and tarsi strongly di- 
lated in the female ; anterior tibiz with one rather short median 
and two smaller and equal apical spurs; intermediate and pos- 
terior tibia each with two pairs of rather long and unequal spurs. 
Abdomen short, somewhat robust. The appendices are compli- 
cated and vary according to the species. 
Larva inhabiting standing and running waters; similar in form 
to Plectrocnemia ; living under and on stones, and drawing to- 
gether débris with light silken threads; several larve often live 
under one common covering. When about to metamorphose a 
case of stones is constructed. 
In the “ Entomologist’s Monthly Magazine,” vol, i. pp. 25— 
31, I have given a resumé of the British genera and species of 
Hydropsychide with tricalcarate anterior tibiz ; the generic cha- 
racters being principally based on differences of neuration. As 
therein stated, the species of this genus divide themselves natu- 
rally into two sections, which some may even feel disposed to 
consider distinct genera. 
A. In the posterior wings, discoidal cell open, forks 1,2 and 5 
} (spoat) ? ’ 
present ; two first coslule united near the middle by a short 
transverse vein. 
