84 BRITISH CHAROPHYTA. 



particularly rich in Charoplijrte-remains and many 

 specific names have been given to them. We are 

 indebted to Messrs. Dollfus & Fritel (3) for a recent 

 conspectus of the various types recognized. The Oligo- 

 cene series of the Isle of Wight .(Osborne, Bembridge 

 and Hamstead beds) abound in remains of these plants, 

 but these have not yet been fully worked out. In the 

 Bembridge beds one of the large medicaginula type of 

 fruits and C. tuberculata are the most prevalent. In 

 the "White Band" of the Hamstead beds C. tuherculata 

 and C. helicteres occur in great numbers, in small ' 'pockets. ' ' 



Miocene. — Charophyte remains, both fruits and vege- 

 tative parts, are plentiful in the Miocene beds, which are 

 not represented in this country. A number of specific 

 names have been given to them. Of the types of fruit 

 the most remarkable is a very large obovoid one, C. 

 Meriani, Braun. 



Pliocene and Pleistocene. — In some of the PHocene 

 and Pleistocene beds Chara-huits are abundant, but, as 

 might be expected, these resemble for the most part those 

 of species common and widely distributed at the present 

 day. In the Cromer Forest Bed, Reid found a large type 

 of fruit which I have little hesitation in referring to 

 Nitellopsis obtusa, and a small rather cylindrical type 

 resembling that of C. connivens. Both of these are com- 

 paratively rare species but both still grow in Norfolk. 

 The vegetative parts of Charas are also present in some 

 of the beds, occasionally forming great masses of so- 

 called " shell-marl," and in all probability many deposits 

 of lime which now show no trace of organic structure 

 originated in the same manner (see Vol. I, p. 11). 



Among the fossil remains of Charophytes no trace of 

 antheridia has up to the present, I believe, been found. 

 This is, no doubt, due to the very delicate thin-walled 

 cells of which this organ is formed. In many of the 

 clay and Limestone deposits detached fruits only are 

 found, and, when accompanied by vegetative remains, 

 the latter are in such small fragments that it is not 

 possible to reconstruct the plant. Occasionally only are 



