24 J. SAtWDEES — NOTES ON THE CHAEACE^. 



at the brink: "Is there another water-hole?" The reply was 

 returned: "Yes, a little further on, near the next willow-tree." 

 A few more steps and this was reached, when fortunately at the 

 second sweep some of the much-desired plant was brought up. 

 A fair supply was obtained, and living plants were forwarded to 

 Messrs. Groves, and also to the Gardens of Cambridge and Kew. 



Geogeaphical Disteibution. 



The Characese are very widely distributed, as is often the case 

 with the fresh-water flora. They are most abundant in temperate 

 regions, but they grow in almost all parts of Europe, Asia, Africa, 

 America, and Australia. Our two commonest Charas, G. fragilis 

 and C. vulgaris, are well-nigh ubiquitous ; as is also our most 

 frequent Nitella, N. opaca. 



The dispersal of the fruits of these plants over such a large 

 area is probably due chiefly to the agency of aquatic birds. The 

 fruits are minute and light, and are frequently lodged in the mud 

 or clay of ponds. Anyone who has observed the margins of these 

 land-locked waters, especially in rural haunts, will have noticed 

 the marks of the feet of birds, and it is easy to see that the fruits 

 of aquatic plants occurring in such conditions might often be 

 carried long distances by the birds. The mud attached to the 

 birds' feet would be softened when other waters were visited, and 

 their contained fruits would be left to germinate if the conditions 

 were favourable. 



Fossil Chaeace^. 



The wide distribution of the Characese also suggests a high 

 antiquity. In this respect, however, they bear no comparison 

 with such ancient types of plants as ferns and equisetums. The 

 earliest known appearance of the stoneworts is in beds of Eocene 

 age, in which they are represented by their curious spherical fruits. 

 These are sometimes present in great numbers and well preserved, 

 showing even their external ornamentation. Through the courtesy 

 of Mr. Henry "Wood, of Cambridge, I have been enabled to prepare 

 for the museum of the Society specimens of these fruits which 

 were obtained from the Eocene beds of Cambridgeshire. 



In this connection may be mentioned the occurrence of these 

 fruits in a semi-fossil condition in the bed of an ancient pond 

 at Hitchin, which was exposed by digging-operations. They are 

 especially interesting in that they form a connecting-link between 

 the fossil Characese of the later geological periods and those of the 

 present time. 



It would be interesting if the evolution of this group could 

 be traced, but the materials at present available are not sufficient 

 for the purpose. During the lapse of time between the close 

 of the Cretaceous period and the beginning of the Eocene there 

 were doubtless many changes in the organic world. The records 

 of this lengthy period are either destroyed or have not yet been 

 brought to light. 



