12 Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



B. Florideæ. 

 I. Nemalionales. 



Fam. 1. Helminthocladiaceæ. 



Subfam. 1. Chantransieæ. 



Acrochætium Nagl. 



After an exhaustive enquiry as to the correct generic name 

 for the plants hitherto usually grouped under Chantransia I have 

 come to the conclusion, in agreement with the opinion, amongst 

 others, of J. Agardh^), Batters 2) and quite recently M. A. Howe 3) 

 that we must adopt Nägeli's name Acrochætium^). 



I will shortly give my reasons for this. 



The genus Chantransia was originally created by De Candolle ^) 

 but, as pointed out by Thuret^), his genus includes forms of 

 genera as different as Lemanea, Batrachospermum, Cladophora and 

 Oedogonium and has therefore nothing to do with the genus 

 Chantransia as now understood. 



It was first Fries') who in 1825 reorganized it more pre- 

 cisely giving as types of the genus the two freshwater forms 

 Conferva Hermanni and Conferva chalybæa Roth. 



But before this Bory^) had already referred these plants to 

 his new genus Aiidouinella. From this fact alone the genus 

 Chantransia Fries ought to be regarded as a synonym when the 

 priority is strictly followed. But the position of this genus 

 became yet more untenable when it was discovered by Sirodot^) 



^) Agardh, J., Analecta Algologica, Lundæ 1892, p. 45. 



2) Batters, E. A. L., A Catalogue of the British marine Algæ (Journ. of 

 Bot., Supplem. 1902, p. 58). 



3) Howe, M. A., The Algæ of Peru (Memoirs of the Torrey Bot. Club, 

 vol. XV, New York 1914, p. 63). 



*) Nag ELI, Beiträge zur Morphologie und Systematik der Ceramiaceæ. 

 (Sitzungsb. Königl. Bayer. Akademie der Wissensch., 1861, p. 402). 



5) Lamarck et De Candolle, Flore Frangaise, t. II, 1805, p. 49. 



*) Thuret in Le Jolis, Liste des Algues de Cherbourg, 1864, p. 104. 



') Fries, E., Systema orbis vegetabilis. Pars I, p. 338, Lundæ 1825. 



*) BoRY DE Saint-Vincent iu "Dictionnaire classique d'histoire natu- 

 relle", t. 3, Paris 1823, p. 340. 



*) Sirodot, S., Les Batrachospermes. Paris 1884. 



