of some South Bi'dziliiai Trlclioptera. 143 



its under part to be comj^ressed until tlie opposite sides 

 touch each other, thus translbrniing the Avide circular 

 opening into a narrow slit. The mouth of the bottle 

 represents the mouth-end of the larval case, and the 

 long narrow slit at the tail-end is held in an upright 

 position. In one species {L. hyalina) the case is quite 

 colourless and perfectly hyaline ; in a second species 

 (Z. Spirogyrcc) it has a dark violet, or brownish, or 

 blackish, colour, darker towards the mouth-end. For 

 transformation the case is placed on one of its broad sides, 

 and then fixed on either side of each end by means of 

 petiolated discs ; at the mouth-end of the larval case 

 there are two discs in Ijoth the species, and as many exist 

 at the opposite end in /,. Spirogi/ra, but in L. hyalina 

 there are four, the petioles dividing before they expand 

 into discs. After having fixed its case the larva turns its 

 head towards the broader end of it, so that the mouth-end 

 of the larval case becomes the tail-end of the pupa case, 

 and vice versa. L. hyalina lives in small rivulets under 

 stones, L. Spirogyroi in slowly-moving or even standing 

 waters filled Avith Spirogyra, Callitriche and Heteranthera 

 reniformis ; the larvaj are to be met with among the 

 Spirogyrce, on which they seem to feed ; the pupte are 

 fixed to the under side of the leaves of Callitriche or 

 Heteranthera. The perfect insects emerge early in the 

 afternoon. 



Genus V. RiiYACOPSYCHE Hagenii. 



The larvne live in rapids of mountain rivulets. The 

 brown coriaceous cases of younger larvEe are nearly 

 cylindrical and widely open at each end, afterwards they 

 are widened in the middle, corresponding to the increasing 

 thickness of the abdomen of the larvje ; from one end 

 there proceeds a string of silken threads, generally about 

 as long, but sometimes even more than twice as long as 

 the cases, by which the latter are fastened to the upper side 

 of stones. Thus the larva is secured against beino; carried 

 away by the current, and at the same time by the mobility 

 of its case its pasture ground is greatly enlarged, and the 

 more so as it can issue indifferently at either end of its 

 tube. It feeds on microscopical alga3. Before its change 

 the string is much shortened and thickened, being thus 

 transformed into a rigid footstalk, able to sustain the case 



TRANS. ENT. SOC. 1879. — PARI IT. (.JULY.) L 



