CHLOROPHYCE^E 127 



Chlvrodictyon, said to be related to Caulerpa, and its 

 description and figure have found a place in several 

 important books of reference. It is however not 

 even an Alga, but a lichen without the least 

 structural resemblance to Caulerpa. 



The Geographical Distribution of the genus is 

 throughout tropical and sub-tropical seas. There is 

 one species (0. prolifera) in the Mediterranean, and 

 several as far south as the Cape of Good Hope. 



The name Caulerpites has been given to a large 

 number of fossil remains without, in a single 

 instance, any reason other than a more or less vague 

 resemblance of outward form. Since the genus 

 itself resembles so many other types, this has been 

 almost an inevitable error on the part of those palaeo- 

 phytologists who choose to be content with mere 

 impressions. A fossil Caulerpa (Fig. 33) from the 

 oolite (Kimmeridge Clay), of which we possess casts 

 in the round, stands on a firmer basis, since it not 

 only exhibits resemblance of form, but occurs in the 

 same beds with a marine fauna of a tropical 

 climate. 



VAUCHERIACE.E. 



General Characters. The order is represented by a 

 single genus Vaucheria, and is the only one among 

 the Siphonem with distinct oogamous reproduc- 

 tion. Its simple, little differentiated thallus and 

 highly developed type of reproductive organs, as well 

 as the possession of non-sexual zoospores and a mode 

 of vegetative propagation, mark it out from other 



