MARINE DIATOMS OF THE PHILIPPINE ISLANDS 5 



It is therefore practically immaterial that a list of the plankton 

 diatoms is not included in this report, as its purpose is to record the 

 truly characteristic diatom flora of the Philippines; that is to say; 

 those species that have their fixed and natural habitat in those 

 waters. 



SIMILARITY OF CAMPECHE BAY AND PHILIPPINE ISLANDS 



DIATOM FLORAS 



A remarkable fact has been brought out by this study of Philippine 

 Island diatoms, their close similarity to those of Campeche Bay in 

 the Gulf of Mexico. How great this really is can only be conjec- 

 tured at present, for a thorough study of the Campeche Bay diatoms 

 has never been undertaken. A more extended examination of mate- 

 rial from there is much to be desired, so as to see how far this inter- 

 esting correspondence goes. But even such meager references to 

 Campeche Bay forms as have been met with in Schmidt's Atlas and 

 other publications during these studies have established the fact that 

 many speoies, and especially many unique varieties, are common to 

 these two localities and rarely if ever found elsewhere. The value of 

 extending this comparison in this particular instance is because there 

 evidently is involved here a certain law or laws of development which, 

 if discovered, will help to explain some curious marine biological puz- 

 zles. For we have in these places a case of extreme isolation from 

 each other, and yet a notable similarity in their diatom flora. Not 

 only are they geographically remote, but the vast barrier of North 

 and South America is interposed between them; so that any connec- 

 tion by means of ocean currents is absolutely out of the question. 

 It should be mentioned that the materials were collected before the 

 opening of the Panama Canal, through which, as time goes on, there 

 will take place a slow but steady transference of small forms of animal 

 and plant marine life. 



At first it might seem equally strange were certain rare species of 

 diatoms discovered to be common to the shores of Alaska and of the 

 Hawaiian Islands; but such a coincidence would be no parallel to 

 this one. For it could well be explained by assuming that the golden 

 plover, as well as certain ducks, curlews, and other shore birds, known 

 to migrate annually between these two remote places were the car- 

 riers responsible for such striking cases of similarity. Or, to take 

 another example, it is now well established that there are currents 

 which bear logs and other drift from northwestern America to the 

 far off shores of the Hawaiian group ; and it is believed that some of 

 the old war canoes found on these islands were made from trees not 

 native there, but indigenous to such remote localities as Oregon and 

 the shores of Puget Sound. Here again a satisfying explanation for 



