432 



Annals New York Academy of Sciences 



all the major groups present, and even some of the existing orders and families 

 already present and showing their characteristic features. 



Our knowledge of fossil algae is limited and very spotty with many vacant 

 spaces both in time, and in algal groups. The study is still in its early child- 

 hood. There are a number of reasons for this. (1) Geologists and paleon- 

 tologists have only recently become interested in fossil algae, and to begin to 

 search for and to study them. (2) The nature of the fossils, (table 4); and 

 (3) the difficulties in accurately identifying and classifying the fossils will be 

 discussed later. 



Thanks to the fact that the oil companies have discovered that algal lime- 

 stones make good reservoir rocks, petroleum geologists and paleontologists are 

 becoming interested in fossil algae. However, as yet, very few have the knowl- 

 edge and experience to use them. I seriously doubt if there are 10 people in 

 the world with a good working knowledge of the subject. In the Western 

 Hemisphere there are only 3 people working full time in the field, and 2 of these 



Table 3 

 Parallelism in Development of Advanced Forms 



are interested only in certain groups. However, there are a number who are 

 learning, and are studying either certain groups or the fossil algae present dur- 

 ing certain geological periods. 



From the very nature of the majority of the algae their chances of being pre- 

 served as fossils are very slight. 



A tiny drop of jelly surrounded by a thin wall of organic material will only be 

 preserved under very exceptional conditions, and even then the chances of it 

 iDeing found are very slight. Normally only those microscopical forms which are 

 encased in a covering of siUca or other mineral material are hkely to be pre- 

 served, as in the case of diatoms and silicoflagellata. Among the larger forms 

 it is also true that the chances of the bodies of such soft organisms being pre- 

 served are almost nil. The only common exceptions are those higher types 

 which have developed the habit of secreting or depositing calcium carbonate 

 within or around the plant tissues, and the microscopical forms which are en- 

 veloped in a siliceous or calcareous covering, or have a hardened encysted stage. 



Groups wilh kmmn fossil representatives (tablf, 5). This program deals with 

 the Protobiota, so emphasis is placed on the microscopical forms. However, 

 other speakers are giving detailed papers on the diatoms, dinoflagellates, and 



