1882.] 67 [Clarke. 



more or less alternating, slender, straight or sinuous, scarcely tapering, 

 slightly divergent, delicate spinules border the shaft on the convex and 

 concave sides, diminishing in length apically and dying out long before the 

 summit is reached, particularly on the concave side; these spinules 

 become altered on this latter side to very long, reversed (or, if the spine 

 be placed vertically, pendent), spatulate appendages at the apical crook, 

 where three of them, increasing in size away from the apex, are attached 

 to the concave surface ; the tip itself is armed on the convex side with a 

 barb or fluke, laterally compressed, and with the tooth or fluke sharply 

 angulate. The whole spine is twice as long as those of the lateral papillae 

 and very much slenderer, rather resembling a barbed hair. None of these 

 appendages can be very fairly compared, as Packard has done (Guide, p e 

 678), to the hairs of Dermestes, at least as these are figured by Riley. I 

 have had no opportunity to examine them. 



Dr. Hagen read the following paper i 



DESCRIPTION OF TWO INTERESTING HOUSES MADE BY 

 NATIVE CADDIS-FLY LARVAE. 



BY CORA H. CLARKE. 



I have found in great abundance in streams near Boston, Mas- 

 sachusetts, some very interesting cases of trichopterous handiwork, 

 together with the architects, — larvae belonging to the family Hy- 

 dropsychidae, and the genus Hydropsyche. The typical form 

 of the structure resembles a tunnel attached to the surface of a 

 stone, having at its mouth a vertical framework with a net 

 stretched across it (see fig. 1 l ). An open mouth or entrance to 

 the case is always close to this net, on the side towards the cur- 

 rent, so that without wholly 

 leaving its house, the larva 

 can remove from the net 

 anything eatable which the 

 current may have lodged 

 there. The mode of build- 

 ing varies considerably. Fig. 1. 

 The case is usually about half an inch long, and a little curved, 



1 Fig. 1 is enlarged about four diameters, the remaining figures are of natural size. 



