40 PROCEEDINGS MANCHESTER INSTITUTE 



although employed diligently, revealed nothing until the rapids 

 were reached. 



At this point the brook flows with a swift current over a rocky 

 bottom and in a curve approximating an arc of ninety degrees. 

 At the foot of the rapids, on the inner side of the curve, a rivu- 

 let enters the brook by a ditch, evidently dug many years ago 

 for the purpose of drainage. The area selected for examination 

 was six feet in length and two in breadth, extending along the 

 inner curve of the brook, including the mouth of the ditch — one 

 foot — and five feet of the rapids. A fine wire netting, of the 

 sort used for window screens, was arranged to enclose the area 

 selected, but a quantitative examination was found to be phj's- 

 ically impossible by reason of the intense cold. For the pur- 

 poses of a qualitative study, however, it is believed that suffi- 

 cient care was exercised to render the collection complete. 

 This collection comprised : 



ID darters (probably a variety of Ktheostoma olmstedi Sto- 

 rer.) 



3 salamanders (young of Amblyostoma ; probably A . puncta- 

 tum, as the characteri.stic dorsal groove was very dis- 

 tinct.) 



2 fresh- water mussels (Unio.) 



8 dragon-fly nymphs (all of the same species, and of the Li- 

 belluline type.) 



14 stone-fly nymphs (evidently two species, but all young and 

 immature) . 



78 may-fly nymphs. 



21 caddis-fly larvae. 



18 dipterous larvae. 



The caddis-fly larvae — some bearing cases of sand, some of 

 sticks, some of leaves, and some of the flattened needles of the 

 hemlock — were found at the mouth of the ditch, with the ex- 

 ception of the sand-case-bearers, which were abundant at ,the, 

 foot of the rapids, but minute, with only the beginnings of 

 cases. The clams were found in the rapids, and all the re- 

 maining forms of life included in the list were also found in 

 in the rapids, among or beneath the stones at the bottom. The 



