84 [April, 



The cases are strongly curved and tapering, 8 to 10 mm. long ; they are russet 

 coloured, sometimes partially blackish, and are so smooth that they look as if 

 altogether membranous ; they seem to be composed of very fine sand or mud fixed 

 to a strong inner silken tube. They are usually found attached to mosses growing 

 in and around trickling springs, which the insect haunts along with Bersea, Cru- 

 noecia, and Diplectrona. 



On the whole, the early stages of Adicella seem to confirm its 

 position between Triaenodes and (Ecetis. The larva bears the same 

 relationship, it may be said, to that of Tricsnodes in the matter of 

 colour and in some other respects as the larva of Bercea does to that 

 of BercBodes. As we find in Beroea the head and prothorax are uni- 

 colorously reddish, and the posterior legs are not of extreme length, 

 and in Berceodes the same segments are greenish, with rich dark 

 markings, while the posterior legs are of great length ; so in Adicella 

 a red unmarked head and prothorax, combined with legs of moderate 

 length, may be contrasted with the longer legs and more decided 

 markings to be found in Tricenodes. 



These points may be held to suggest a certain correlation between 

 a red uniform colour, posterior legs of moderate length, and habits 

 more or less concealed, and between a greenish colour with a pattern, 

 long posterior legs, and more light seeking habits. In the Hydro- 

 psychidcB something almost parallel may be found, at least as regards 

 colour, if the groups of Philopotaonus and Wormnldia are contrasted 

 with those of Plectrocnemia and Polyceoitropus. 



EXPLANATION OF FIGURES. 

 Larva. 



1. Mandible, left from above. 



2. do. right do. 



3. do. left from beneath. 



4. do. right do. 



5. Antenna. 



6. Labrum from above. 



7. Maxillae and labium from beneath. 



8. Lateral protuberance and chitinous band. 



Nymph. 



9. Mandible. 



10. Labrum. 



11. Appendages. 



13, Blackford Road, Edinburgh : 

 February \st, 1904. 



