CHLOROPHYCE 4 127 
Chlorodictyon, 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 Cawlerpa. 
The Geographical Distribution of the genus is 
throughout tropical and sub-tropical seas. There is 
one species (C. 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 palzo- 
phytologists who choose to be content with mere 
impressions. A fossil Cauwlerpa (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. 
VAUCHERIACES. 
General Characters.—The order is represented by a 
single genus Vaucheria, and is the only one among 
the Siphonee 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 
