164 THALLOPHYTA. [CH. 



The restoration of Ovulites, shown in fig. 33, K, bears a striking 

 resemblance to the figure of an Australian Penicillus given by 

 Harvey in his Phycologia Australica\ 



It is probable that these Eocene forms agreed closely in 

 habit with the recent species of Penicillus. The portions 

 preserved as fossils are segments of the filaments which 

 probably formed a terminal brush of fine branches supported 

 on a stem. The retention of the original generic name Ovulites 

 is on the whole better than the inclusion of the fossil species in 

 the recent genus. The Tertiary species lived in warm seas of 

 the Lower and Middle Eocene of England, Belgium, France and 

 Italy. 



Halimeda. 



An example of an Eocene species of Halimeda has been 

 recorded by Fuchs from Greifenstein under the name of 

 Halimeda Saportae^. The impression has the form of a 

 branched plant consisting of w^edge-shaped or oval segments, 

 and there is a close resemblance to the thallus of a recent 

 Halimeda, e.g. H. gracilis Harv. It is not improbable that 

 Fuchs' determination is correct, but without more definite 

 evidence than is afforded by a mere impression it is a little 

 rash to make use of the recent generic name. 



y. Dasycladaceae. 



In this family of Siphoneae are included a number of 

 genera represented by species living in tropical and subtropical 

 seas. 



The thallus consists of an elongated axial cell fixed to the 

 substratum by basal rhizoids, and bearing whorls of lateral 

 appendages of limited growth which may be either simple or 

 branched. Many of the lateral branches bear sporangia or 

 spores. The thallus is in many species encrusted with car- 

 bonate of lime. 



1 Harvey (58) Vol. I. PI. xxii. fig. 3. 



2 Fuchs (94). 



