of some South Brazilian Trichoptera. 133 



long hairs, by the aid of Avhich the piipre of other Tri- 

 choptera swim to the surface of the water when they are 

 about to undergo their final transformation. 



In those species of Helicopsyche, which I have bred, 

 the jjerfect insects used to emerge from the pupse soon 

 after sunset. 



LEPTOCERID.E. 



Of JVI'Lachlan's first section of this family I have not 

 yet seen here any species. 



SECTION II. 

 Two of our genera appear to belong to this section. 



Genus I. 



(Near Odontocerum,i\io\^^\ distinguished by numerous 

 differences. Antennte not dentate ; eyes of the $ 

 very large, meeting on the vertex in one species and 

 nearly so in another ; radius of the anterior wings 

 confluent at its apex with the first apical sector, &c.) 



The case of the larva is a slightly-curved, cylindrical, 

 firm tube, built Avith sand grains ; the tail-end is closed 

 with a transverse wall, having at its upper or dorsal margin 

 a rather large oval or semicircular opening. Before its 

 change the larva cuts a portion of the tail-end of its tube 

 and then fixes the ventral side of either end and closes 

 them by a single stone (in one species), or by a wall built 

 of several fi-agments of stone (in a second species), in such 

 a way that there remains at the ventral side of each 

 extremity a narrow crescentic slit, the ventral margin of 

 which is beset with a row of teeth. It is curious that the 

 manner of closing the tail-end should be quite different in 

 the larva and in the pupa cases. The pupa has five pairs 

 of corneous patches at the basis of the abdominal segments 

 (from third to seventh), each of the patches bearing a single 

 blunt tooth, and there is the usual pair of patches at the 

 end of the fifth segment, having two short sharp teeth. 



The perfect insects emerge from the pupn3 in the even- 

 ing, generally later than Hclicopsyclie. On this occasion 

 the fasciculate branchia; of the pupa are shed, like those 

 of Ephemerido', and this is the most remarkable feature of 

 the genus ; for it appears, that in most Trichoptera the 



