140 Dr. Fritz Miiller's Notes on the Cases 



Genus IV. Rhyacophylax, nov. gen. 



(Appears to be nearly related to Smicridea, but the 

 number of spurs is different, being 1, 4, 4 in the $, 

 and 1, 4, 2 in the $ .) 

 This is, no doubt, as to the cases, the most curious of 

 all our Hydropsychidce. The cases themselves are rather 

 rude canals, covered with irregularly-interwoven vegetable 

 fibres, but at its mouth -end each case has a large funnel- 

 shaped verandah, covered with a very beautiful silken net. 

 The larvte live in the rapids of various rivulets, and the 

 entrance of the verandah is invariably directed towards the 

 upper part of the rivulet, so as to interce})t any eatable 

 things brought down by the water. Generally, a more or 

 less considerable number of larvje build their cases close 

 together, so as to form transverse rows, on the upper side, 

 of stones. Lately, I saw, on a large stone, about half-a- 

 dozen parallel rows, at some distance from one another; 

 one of them, being about 0.2 m. long, must have been 

 composed of about thirty cases. Before the end of the 

 larval period the vegetable fibres are replaced by small 

 stones, and the verandah is destroyed, either by the larva 

 or by the ciuu-ent of the water. One day, when I was 

 taking to my house a stone with beautiful Rhyacophylax 

 cases, some of the larvas left their houses, crept to the 

 edge of the stone and then descended, suspending them- 

 selves in the air, like spiders, by a thread of silk. The 

 larvse of Grumichella, also, may be seen suspending them- 

 selves in the water in a similar way. Such a faculty must 

 prove highly serviceable to larvse living in rapids, Avhere 

 they might otherwise be easily swept away by the current. 



RHYACOPHILIDiE. 

 Genus I. 



(Spurs of a (? pupa 2, 4, 4.) 



The larva lives, principally,. Avithout any case, between 

 the entangled stems of various Podosiemece, which 

 densely cover the stones in the rapids of the Itajahy 

 and its tributaries. It is carnivorous, fragments of insect 

 larvae {Hydropsychidce, Perlidce, &c.) being found in its 

 intestines, and its anterior legs are armed with very 



