July 18, 1967 I visited a eutrophic pool between Mulhouse and Belfort, about 4 km southwest of Les Errues just before the branching of the road to Les Chavannes. The pool is situated close to the main road on the right side. It has a muddy shore and was surrounded by a Carex meadow. Besides specimens of Ischnura elegans (Vander L.), Coenagrion puella (L.), Erythromma najas (Hans.), Libellula depressa L., Orthetrum cancellatum (L.) and Sympetrum danae (Sulz.) there were about 20 males of O. albistylum on the wing above the water. Very often I saw "territorial” fights between this species and O. cancellatum. It was easy to distinguish from the latter by its more cylindrical (not depressed) abdomen and strictly contrasted black abdominal end. It might be noteworthy, too, that E. najas usually flying over the floating leaves of Nuphar, Nymphaea, Potamogeton and others, was found here on little mud bunches rising above the water surface. A zone of floating leaves was lacking totally at this pool. Propagation seems to be impossible under such conditions. Therefore either this population was not autochthonous or the pool had just been "cleaned” from such vegetation.