PLANKTON OF THE GULF OF MAINE 



347 



The large Staurophora no doubt takes a very heavy toll of Calanus and smaller 

 copepods, which are often to be found entangled along the elongated lips of its cruci- 



Fig. 96.— Occurrence of the hydromedusa Staurophora mertensii. X. locality records, summer ot 1912; • subsequent 

 years. The hatched curve includes its chief zone of occurrence within the Gulf of Maine 



form mouth opening, and since the young Staurophora also feed on them greedily, 

 according to Hartlaub (1899), this medusa must play an important role in the natural 

 economy of the animal plankton wherever it is plentiful. 



