British Species of Caddis-jlies. 125 
are furnished with fleshy papillae, which usually disappear in dried 
specimens ;* inside this is the opening whence the eggs are pro- 
truded. 
Larva with the head small and nearly quadrate, truncated 
anteriorly, and furnished with short and broad internally-dentate 
mandibles ; pronotum transverse, shorter than the head, corneous ; 
mesonotum broadly transverse, also corneous; metanotum broadly 
ovate, with a large corneous plate above. (See Pl. II. fig. 15.) 
Legs short, the posterior the longest, slightly hairy. Abdomen 
subcylindrical ; on the ventral surface of each segment there is a 
dense tuft of respiratory filaments on each side; these are even 
found on the under-side of the thoracic segments; anal segment 
furnished with two long processes surmounted by horny hooks and 
long hairs. Case an irregular fixed heap of stones, in which the 
pupa (PI. IT. fig. 20) lies free. Inhabits running streams. 
Considering that most of them are of moderately large size, the 
species of this genus are perhaps the most difficult of all to satis- 
factorily separate. ‘he anal appendices, so certain and evident in 
their characters in most genera, here present very few differences 
in the various species; besides, as many of the parts are mem- 
branous or fleshy in their nature, they dry up into very different 
forms in dead individuals of one species; however, these usually 
all-important characters are not to be despised even here, and an 
attentive examination of living specimens may yet help to clear up 
much of the uncertainty surrounding this perplexing genus. 
A. Third joint of the maxillary palpi longer than the fourth. 
Antenne scarcely so long as the nings ; the jaints not marked 
mith oblique dark lines, (Small species.) 
~ 
1. Hydropsyche albipunctata, Stephens. 
(Pl. VII. fig. 2 e, maxillary palpus.) 
Tinodes albipunctatus, Steph. (*) Ill. p. 164, 7 (1836); Hy- 
dropsyche angustata, Pict. Recherch. p. 208, 10, pl. 19, fig. 6 
(1834)?; Steph. Ill. p.174, 9; H. ventralis, Curt. (*) Brit. 
Ent. p]. 601 (1836)?; H. lepida, Hag. Ent. Ann. 1861, p. 13, 
105 (not of Pictet). 
Antenne brown, the basal portion annulated with yellow. 
Head and prothorax thickly clothed with yellow hairs. Palpi 
* It is probable that the number and position of these papilla may be a 
means of specific diagnosis ; but from the fact of their disappearing in drying, 
the application of the character becomes almost impossible, 
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