NO. 10 DAWSON : MARINE ALGAE, GULF OF CALIFORNIA 337 



GENERAL SUMMARY AND CONCLUSION 



Since the last report on the algal flora of the Gulf of California, the 

 number of species known from that region has been almost trebled (to 

 273 species). Thirty species previously described from or attributed to 

 the area have been reduced to synonymy, sixty-two more described as new. 

 The Gulf has proved to have not only a rich and varied marine flora 

 but one containing species of exceptional distribution. 



The seasonal alternation of floras has been investigated for the first 

 time and has proved strongly marked in the northern regions of the 

 Gulf. A beginning has been made in ecologic investigation. The remarka- 

 ble temperature conditions have been recorded and related to the dis- 

 tribution of algae as far as the evidence allows. Corelation between oxy- 

 gen content of the water and the distribution of algae has been made 

 with very interesting results. The infrequency of temperature and oxygen 

 records, however, leaves much room for future investigation throughout 

 the Gulf. Before the ecology of the marine plants of the region can be 

 satisfactorily understood, complete series of data for all seasons will be 

 necessary. As yet seasonal alternation of floras has been observed at only 

 one station. Turner's Island. The rich floras of Puerto Refugio, Pond 

 Island, San Esteban Island, Tepoca Bay, and the region of Guaymas are 

 inadequately known ecologically and should be investigated at various 

 times of year, particularly in spring and fall. The nature of development 

 of algae, particularly in summer, should be investigated on all shores of 

 the southern part of the Gulf where records now are infrequent or lack- 

 ing. The sublittoral flora is still scantily known, and further dredging 

 operations will undoubtedly be richly rewarded. 



Most remarkable of the species now known from the Gulf are those 

 exhibiting widely discontinuous distribution between the eastern and 

 western sides of the Pacific Ocean such as Ishige foliacea, Lomentaria 

 catenate, Lomentaria hakodatensis, Ceramium paniculatum, and Herpo- 

 siphonia subdisticha. Further ecologic investigations of these and other 

 such plants will undoubtedly help to broaden our views on phytogeogra- 

 phy among the marine algae. 



Cutleria Hancockii is perhaps the most unusual discovery for our 

 region. It is the first member of the essentially Mediterranean order 

 Cutleriales to be found on the Pacific American coasts. Other such 

 novelties awaiting discovery will further add significance to the excep- 

 tional marine flora of this remarkable body of water. 



