CHONDRUS. 431 



The natural order Gigartinaceae includes nine British 

 genera, namely, Chondrus, Gigartina, Phyllophora, Steno- 

 gramme, Gymnogongrus, Ahnfeltia, Actinococcus, Callo- 

 phyllis and lastly Callymcnia. Of these the representa- 

 tives are all fairly well developed plants, with the excep- 

 tion of the species belonging to the genus Actinococcus. 

 One of these has been shown to lead a parasitic life on 

 Phyllophora Brodicei. 



The genera Chondrus and Gigartina differ from the 

 remaining members of the Gigartinacese in their structure. 

 They show internally a very well marked hyphal arrange- 

 ment of the cells — their internal tissues in the younger 

 plants consisting of fairly loose filamentous cells. The 

 central tissues of the other genera are, with the exception 

 of Actinococcus, far more compact and pseudoparenchy- 

 matous. The species of Chondrus have a flattened plant body 

 or thallus. The carpospore-. in the fruit or cystocarp are not 

 surrounded by any special fibrous integument. The latter 

 is one of the distinguishing features of the species of the 

 genus Gigartina. 



Chondrus crispus is the only species of its genus 

 occurring in British waters, and therefore in the L.M.B.C. 

 district. Quite a large number of varieties are dis- 

 tinguished, but I have not referred to these in this memoir, 

 as I consider their recognition to be of no general value. 



The genus Chondrus was founded by Staokhouse— the 

 name crispus was given to the species by Linnaeus. The 

 latter, however, placed the species in the genus Fucus, to 

 which he referred almost every seaweed. Stackhouse 

 removed the species, and gave it a place in the genus 

 Chondrus, where it has remained ever since. Its name 

 therefore runs thus : Chondrus crispus (L.), Stackh., or, 

 according to a certain number of German Algologists, 

 Chondrus crispus, L. sp. They wish to indicate merely 



