PLANKTON OF THE GULF OF MAINE 



419 



I may add, for the sake of completeness, that much the same list of diatoms 

 occurred over the whole breadth of the continental shelf off Shelburne, Nova Scotia, 

 on March 19, 1920 (stations 20073 to 20076), though here the variety of species per 



71' 



Fig. 116.— Occurrence of certain neritic diatoms in February and March, 1920, a dot for each locality record of the following 

 species: Biddalphia aurita, Chxtoceras debile, Ch. eontortum, Ch. diadema, Ch. didymum, Ch. lacinioaum, Ch. mitra, Ch. 

 sociale, Eucampia, Lauderia glacialis, Licnophora, Skelctonema, Thalassiothru nitschioides, and Thalassiosira. The 

 hatched curve incloses the area where most of the stations yielded Ave or more of these species; the stippled curve where 

 we found none of them 



station averaged larger than in the neighboring parts of the Gulf of Maine, as, for 

 example, in Browns Bank, in the Northern Channel, and along western Nova 

 Scotia. The most interesting feature of the diatom communities along this line is 



