1890.] 39 



In support of the latter idea, I may mention that I long failed in my 

 attempts to rear T. aureola until I discovered that the larva would 

 only live in the shallowest of water ; and besides, the tarsi of the 

 jUiiddle pair of legs in the nymph have no fringes, the absence of 

 which is characteristic of species frequenting springs, or rocks wetted 

 with the spray of the water falls {cf. Fritz Muller, Trans. Ent. Soc. 

 Lond., 1879, pp. 132—138). 



While thus the larvae of T. wcsneri are often found at considerable 

 depths, and those of T. aureola are usually little more than covered 

 with water, the habitations of the two species hardly differ, save in 

 size, and consist of a long ribbon-like web, externally strengthened by 

 slight additions of sand grains and other matter, attached by its edges 

 to rocks and large stones in serpentine fashion, thus forming a kind 

 of half cylinder, the diameter of which is just exactly sufficient to 

 admit of the larva turning itself. These covered canals are rapidly 

 made, and are often very long ; one belonging to T. aureola is noted 

 by me as 2 mm. in breadth and 23 mm. long ; these measurements, 

 however, are often exceeded, and in T. wceneri may reach double the 

 foregoing figures or more. They are usually partially closed at one 

 end, being rounded off and perforated with little holes ; but they are 

 constantly undergoing change or extension, and as the larvae seem to 

 obtain their food principally by consuming large quantities of mixed 

 matter, such as adheres to rocks and stones, they probably serve as 

 covered ways for the inmates in their search for fresh feeding grounds. 

 Of course quantities of edible matter will also be carried into the 

 canals on the currents caused by the flexions of the larvae. The 

 abundant frass is composed largely of sand, and takes the form of 

 very long cylindrical pellets. Perhaps, rarely, these larvae are pre- 

 daceous. 



In most of the instances which have come before me in rearing 

 these insects, the nymph-cases have been elongated cells strengthened 

 with sand grains, constructed within the larval habitations. A nymph- 

 case of T. ivceneri was made in the angle at the bottom of a small 

 bottle, and was an elongated silken cell, only very slightly strengthened 

 with extraneous matter (probably on account of its not being at hand), 

 with a network at either end, one of them placed a little towards the 

 upper-side of the case, rather than at the actual extremity. Length, 

 7| mm. 



Klapalek, in his useful essay, " Metamorphose der Trichopteren," divides the 

 larvae of caddis-flies into two Sections, indicated by the terms — " raupenformig " and 

 " campodeoid." The larvae now under consideration belong to the second form, and 



