March, I9I3-] SlEIGHT : TrICHOPTERA, 7 



The lower (Helicopsyche annidicornis Banks) is formed of fine 

 grains of sand of uniform size, cemented together with silk into 

 the shape of a snail shell. As a matter of fact, it is said to have 

 been described as a species of snail. The pupal cases are found 

 attached to sticks, stones, and cases of larger Trichoptera. 



The fifth species (Psilotreta frontalis Banks), found all the way 

 from rather swift current to nearly still water, although quite common 

 about Ramsey, is not recorded in Smith's list, nor even the family 

 Odontoceridse to which it belongs. The cases are made of small 

 uniform grains of sand. 



The next species is usually found in places having slightly less 

 current, but never in absolutely still water. Their cases are some- 

 what similar to the previous one, although they taper more at the 

 posterior end and are made of finer sand. 



The wide flat sand case (Molanna cinerea Hagen) comes next in 

 the series. It is not to be found in absolutely still water, although it 

 does not occur where the current is even moderately strong. 



The branched case is very different from the usual type of Tri- 

 choptera cases. There are several species differing slightly among 

 themselves, but all apparently belonging to the genus Polycentropus. 

 All but the upper tips of the cases are buried in the mud or sand. 

 For the most part they are found where there is a very slight current, 

 but they extend their distribution even up to the strong current and 

 down to the absolutely still water. Those in the slight current of 

 streams are built of sand, while those in the still water of ponds use 

 very fine pieces of vegetable matter. The cases of some species 

 are straight, others are branched as shown ; some are of uniform 

 diameter while others have enlargements, forming cells in which the 

 larva rests, but all are imbedded in the bottom. Where the mud is 

 deep the cases are much longer than where there is little or no mud. 



We come now to those species which are typical of absolutely 

 still water. The first, Platycentropus maculipennis Kolen. =• Halesus 

 hostis Hagen, it is true, occurs all the way up to rather strong cur- 

 rent, but it becomes more abundant as the strength of the current 

 decreases. Its case is made of bits of leaves — duck-weed being fre- 

 quently used. 



The last (Phryganea interrupta Say) is found only in still water. 

 The cases are smooth cylinders formed of pieces of leaves. The 



