Abstract
Cells identified as Catenula adhaerens were studied from marine and brackish-water sites on European coasts, along with the type specimen of Amphora sabyii and valves identified as A. sabyii from California. All these specimens agree well with Mereschkowsky's description of C. adhaerens. Thus, Amphora sabyii is conspecific with C. adhaerens, as already suggested by Simonsen. We present evidence that Catenula should be kept separate from Amphora. C. adhaerens appears to be a cosmopolitan epipsammic marine species.