British Species of Caddis-flies. 93 
rather long median, and two apical spurs in the male (only the 
apical spurs in the female); posterior tibize with two pairs of 
rather long spurs. Abdomen slender; stouter in the female, in 
which sex the apex is acute. 
Larva with small head -and thoracic segments; abdomen much 
dilated ; no external respiratory filaments. (See Pl. II. fig. 4.) 
Case oval or reniform, membranous. (See Pl. II. fig. 31.) In- 
‘habiting both standing and running waters. 
Such are briefly the only characters that I can give of this most 
puzzling genus. I confess that I have never been able to satisfy 
myself, from personal observation, as to the comparative lengths 
of the joints of the palpi, and scarcely as to the number of these 
joints. 
The characters given by various authors are very discordant. 
Dr. Hagen has lately sent me specimens (in alcohol) of a minute 
insect taken in Prussia, which, although it bears a complete 
superficial resemblance to what he and I consider as Hydroptila, 
is nevertheless very different in structure, so much so in fact, that 
it cannot even be placed in this family. The maxillary palpi are 
five-jointed in both sexes, the two basal joints being very short ; it 
possesses large and evident ocelli, and the spurs are 0-3-4 in both 
sexes ; besides these characters the posterior wings do not appear 
to me to be excised on the costal margin. The existence of this 
form (which may probably be found in this country) may par- 
tially account for the discrepancies in the published characters of 
Hydroptila, but these are no doubt in a great measure due to the 
extreme minuteness and hairiness of the insects. 
That the species I consider as Hydroptila really belong to that 
genus as figured by Dalman, I have little doubt, but Dalman 
mentions that the anterior tibize are spurred at the apex. Neither 
is Dr. Hagen nor am I aware of the existence of any similar form 
with this character, but Dr, Hagen informs me that he possesses 
Hydroptila, or at any rate an insect of the same form, in which 
the spurs are 0-2-4 in both male and female. 
The following is a brief reswmé of the principal characters as 
given by various authors. Pictet says, ‘‘ palpes maxillaires 4 cinq 
articles dans les deux sexes,” but gives nothing whatever about 
the spurs: unless he had the insect noticed by Dr. Hagen before 
him, I imagine that he has not rightly defined the number of 
joints, Zetterstedt omits all description of the parts of the mouth, 
and gives the number of spurs on the posterior tibiz only. Bur- 
meister places Hydroptila in his first section, ‘ Kiefertaster bei 
beiden Geschlechtern 5-gliedrig und von gleicher Gestalt;” with 
respect to the spurs he says, ‘die vordersten ohne oder mit sehr 
