Cladophoracetr 



103 



causes them to be frequently loaded with epiphytes. Very often 

 the older filaments are thickly covered with Diatoms, particularly 

 of the genera Gomphonema and Gocconeis. 



Genus Chaetomorpha Ktitz., 1845. The filaments are simple, 

 of more or less uniform thickness 

 and fixed at the base, the lower 

 segments being shorter than the 

 upper ones. The segments are 

 often slightly swollen and they 

 are of considerable diameter. The 

 cell-wall is thick, very firm and 

 obviously lamellose. 



Most of the species of this genus 

 are truly marine or brackish in habit, 

 but Ch. sutoria (Berk.) Eabenh. (fig. 3S) 

 is sometimes found in running water, in 

 we] Is and horse-troughs, or in streams. 

 Diameter of filaments 100 120 p. 



Genus Rhizoclonium Kiitz., 

 1843. The filaments are of vari- 



Fig. 38. Cluetomorphasutoria (Berk.) 

 Eabenh., from Heaton, W. Yorks. 

 ( x 100). 



able size, crisp, generally branched, and attached at the base by a 

 branched hapteron. The branches are short, slightly attenuated, 

 sometimes merely unicellular outgrowths, but more frequently 

 consisting of several cells. The filaments are often bent at the 

 point of origin of a branch. The cell-walls are firm, lamellose, 

 and sometimes attain a considerable thickness. The number of 

 nuclei present in each segment is variable and the chloroplast is 

 in the form of a network containing several pyrenoids. The most 

 recent account of the structure of this genus is by Wille 1 , who 

 confirms much that has been described by Gay 2 . Stockmeyer 3 

 has given a thoroughly good systematic account of the genus. 



In the autumn the segments of the thallus are often packed 

 with starch. 



Species of this genus are marine, brackish, freshwater, or they may even 

 occur on damp soil. The only freshwater British species is R. hieroglyphicum 

 Kiitz.; em. Stockm. [= Conferva fontinalis Berk.; Microspora fonti'milis De 



1 Wille, 'Studien iiber Chlorophyceen VII,' Vid.-Selsk. Skrifter. M.-N. Kl. 

 Christiania, 1900. 



2 Gay, 'Eecherches sur le devel. et la classif. de quelques Algues Vertes,' Paris, 

 1891. 



3 Stockmeyer, ' Uber die Algengattung Rhizoclonium,' Verhandl. der k. k. 

 Zool.-Bot. Gesellsch. in Wien, Jahr. 1890. 



