30 



note that even to reach the furthest extremity of an arm, the last four 

 segments of the body need not be exposed outside the case, nor are 

 there any other actions which require further extension of the body. 



Larva No. 18 is slightly smaller than C. pusio. It builds a still 

 more elaborate case, composed of a long stalk to which is attached a 

 short tube with three long arms given off at the free end ; the case is 

 not quite so opaque as that of C. pusio, and is of a lighter brown 

 colour. 



Larva No. 19 I found in a fixed tube attached along part of its 

 length to the stems of moss. The tube was composed of fibres and 

 very small sticks placed transversely in the same fashion as is done by 

 Liuniophiliis ronibicus (Trichoptera) in making its free case. Another 

 larva, No. 10, feeding on Starwort (Callitriche verna) and living in 

 ponds, builds a fixed case composed of short lengths of the starwort 

 leaves placed longitudinally round the body. All the abdominal seg- 

 ments except the last two bear 8-10 branched hairs in a similiar position 

 to the bifurcators of C. pusio. Possibly they have the same function 

 as in C. pusio. The cephalic-brained larva No. 17 is interesting ; it is 

 found in swift running brooks, buried in little tangles of Spirogyra. 

 which it apparently works into oblong masses in which two or three 

 larvae are generally found together. The green masses are found moored 

 to the water-worn pebbles, and swaying freely in the stream. Larva 

 No. 5 builds perpendicular tubes rising up from the bottom of deep 

 muddy pools to a length of 10 cm. In order to accomplish this feat 

 two or three larvae generally build their tubes side by side in order 

 to gain mutual support, but when the tubes are finished they appear 

 as one, and are then about 3 or 4 mm. in diameter. It still remains 

 to be found out by what method this larva procures materials for its 

 long tube, as there is no net formed at the free end and generally 

 there is no flow of water to bring particles; possibly it brings up mud 

 from the bottom of its tube, but of this I have no evidence. 



If a larva of of C. Pusio be taken out of its tube, and placed 

 in a dish containing water with a little mud suspended in it, and 

 also a little sediment lying on the bottom, the whole process of case- 



