142 Dr. Fritz Miiller's Notes on the Cases 



prove to be one of the most numerous Trichopterous fami- 

 lies in tliis country, including the most varied and remark- 

 able larval cases. 



Genus I. 



There are here various species, the cases of which 

 resemble more or less closely the well-known cases of 

 Phrixocoma pulchricornis, being much compressed from 

 the sides and opened by a narrow slit at each end. They 

 are either naked, or covered with very fine sand, or "wath 

 algfB or diatoms, which in one species are arranged in an 

 extremely elegant manner. The cases of the pupse are 

 fixed either along the Avhole ventral margin or at the two 

 ends, or in one species, abounding on the rocks of water- 

 falls, at one end only. 



Genus II. 



Very miniite, nearly cylindrical, coriaceous, brown 

 tubes ; covered with very fine sand, Avhich in the pupa 

 state are fixed at either end to the underside of stones, 

 showing generally two adhesive discs on the anterior, and 

 a single one on the posterior end. They are common 

 almost everyAvhere. 



Genus III. DiAULUS Ladislavii. 



Strongly-compi'essed oval cases, elegantly covered with 

 diatoms, with a naiTOw slit at each end, and liaAdng on 

 the dorsal margin two (or, as I have seen in one specimen, 

 three) cylindrical chimneys. The observation of living 

 larvEe of this and of the first genus leaves no doubt as to 

 the use of the chimneys. Those inhabiting cases opened 

 only by a slit at each end are seen moving incessantly, and 

 working very hard, in order to maintain a current of water 

 through these narrow passages ; those of Dimilus, on the 

 contrai'y, may remain motionless for a very long time, the 

 water necessary for respiration having a free access through 

 the chimneys. The cases of the pupre are fixed in an 

 upright position along the whole . ventral margin on the 

 upper side of stones, and often these little houses form 

 large villages of a rather picturesque aspect. 



Genus IV. Lagenopsyche. 



An approximative idea of the cases may be fomied by 

 imagining the bottom of a bottle to be cut away and then 



