148 The Irish Naturalist. [July, 



The group contains 150 species, some of which like Chara 

 fcetida are cosmopolitan. Twenty-eight species are found in 

 Great Britain. Twenty are recorded for Ireland in the new 

 edition of the "Cybele Hibernica." A detailed account of their 

 distribution in Ireland appears in the Irish JVaturalist for 1895, 

 by the brothers Groves, who have made a special study of the 

 British Characeae. The publication of their fasciculi of dried 

 specimens has made the stud}' of the group much easier, as has 

 the recent completion of Migula's fully illustrated Monograph 

 "Die Characeen" in Rabenhorst's " Kryptogamen- Flora," an 

 abridged form of which has more recently appeared. 



The collecting of Characeae is helped by the use of a small 

 hook dredge. Owing to their entangled and brittle character, 

 special care is needed both in collecting and mounting 

 specimens. 



The following key is practically an adaption of the one in 

 Migula's work and that by the Groves brothers in the Journal 

 of Botany, 1880, to which periodical many illustrated papers 

 on different Characeae have been contributed by these botanists. 



Tolypellopsis is a very interesting connecting link between 

 the Chares and the Nitellecs, and is regarded by Migula as 

 the oldest living representative of the Characeae. Its oospores, 

 oosperms, or nucules show a close likeness to those of a fossil 

 type. They are rarely fully ripened, reproduction being 

 essentially vegetative. The genus has a very isolated geo- 

 graphical distribution, indicative of a waning character. 

 Tolypellopsis stelligcra, Mig. is recorded from England but is 

 an Irish desideratum. Of the six genera only three — Nitella, 

 Tolypella, and Chara — are Irish. 



KEY TO THE CHARACEAE. 



A. Crown or corona of 2-celled filaments, i.e., crown is 10-celled. 



I. Nitei^E^. 



a. Leaf or ' branchlet ' with only one leaflet or ' ray '-producing 



node. 

 Leaflets projecting beyond leaf-tip, often themselves again 

 branched ; Antheridia apical, on the leaf or leaflet of the 

 penultimate order. 1. Nitella. 



b. Leaf undivided or having shorter lateral leaflets ; Antheridia 

 terminal on i-celled lateral leaflet; 2. Tolyf>ella. 



