April, '05] ENTOMOLOGICAL NEWS. II3 



Oviposition in Cordulcgaster. 

 ; By Dr. F. Ris, Rheinau, Switzerland. 



Prof. Needham's very pleasant narrative in the January 

 number of Entomological News reminds me that I might 

 give an account of an observation that seems not 3et to have 

 been recorded. 



There is, ver}' close to Ziirich, almost within the limits of 

 the city, a locality where, many years ago. I used to collect 

 our two Swiss Cordulegasters, bidejitatiis and ajinulatus, the 

 first always about ten days earlier than the other more widely 

 diffused and less appreciated species. The place is a small 

 open space in the woods, rather steeply inclined, the exposure 

 nearly due North. Notwithstanding the inclination, the 

 ground is swampy- — we are in a region of beautiful and well 

 preserved deposits of the great Ice Age — and a small spring of 

 clear water runs down the slope, collecting at its foot in a shal- 

 low pond, thickly overgrown with various sedges. Menyaiithes 

 trifoliata, etc. This spring and pond are rich in Neuroptera ; 

 I mention Adicella filicornis, Cnincecia irrorata, Bema artiai- 

 laris, BercEodes niimita, Ptilocolepus granulatus, Oxyethira fal- 

 cata, amongst the less common Trichoptera, and they are the 

 haunt of the Cordulegasters, the only one in the neighborhood 

 of Zurich where I found them regularly and in numbers. The 

 quality of the water is somewhat peculiar, not for this country, 

 but more generally speaking ; it is very rich in lime, as are all 

 such springs in our rigion, where glacial deposits cover the 

 rock of soft tertiary sandstone. Every branch of moss, every 

 rootlet, every dead leaf, that hangs or falls into these waters is 

 in a very short time covered by a soft deposit of soft, porous 

 limestone. These deposits soon crumble and form in the rivu- 

 lets a bottom of small, sharp-edged, angular debris, quite dif- 

 ferent from soft mud or polished gravel as they exist in our 

 larger waters. I think this detail is not without importance in 

 connection with the Cordulegasters. 



Last summer I visited the Cordu/egasier-spnug again, after 

 many year's interruption, on June nth. The season was an 

 unusually early one ; I came just at the best of C. bidentatuSy 



