414 



Nostocacées hétérocystées, one will see. that the only difference 

 urged is the difference of thickness of the filaments and trichomatas. 

 Without doubt it is a mistake to establish species on differences of 

 thickness only. Other discriminating characters would be necessary, 

 and that such are not to be found here, authentic specimens have 

 proved. Moreover several of the specimens examined by me had a 

 measurement which was between the measurement given by Born et 

 & Flahault for T.lanata and T. tenuis, and where should the limit 

 come, if we once admit the right of establishing species on differences 

 of size only? 



It may be remarked, that the sheaths of this species not are 

 always thin as said by Bornet & Flahault; sometimes the older 

 ones are thick and lamellose. 



97. Calothriv scopuloruin (Weber et Mohr) Agardh emend. 



Calothrix scopulorum Agardh. 

 Systema Algarum, p. 70, 1824. 

 Calothrix scopulorum Bornet & Flahault. 

 Revision des Nostocacées hétérocystées , fragment I , p. 353, 

 e specim. authent. in herb. Ham. 

 Calothrix fasciculata Agardh. 



Systema Algarum, p. 71, 1824, e specim. Agardhi in herb. 

 Hofman-Bang. 



Calothrix fasciculata Bornet & Flahault. 



Revision des Nostocacées hétérocystées, fragment I, p. 361, 

 e specim. authent. in herb. Ham. 



T hallo velutino late expanso, caespitoso-pannoso, atro-viridi, 

 atro-olivaceo, vel fusco. F il i s usque ad 3 mm. longis, 10 ju ad 

 24 p. crassis , basi saepe paullulum inflatis , plus minus flexuosis 

 et tortuosis vel interdum fere recti's , simplicibus vel plus minus 

 crebre pseudo-ramosis, ramificatione duplici: 1) ramis patentissimis 

 paucis, singulis vel geminis; 2) ramis erecto-adpressis plus minus 

 numerosis ad partem superiorem et mediam filorum fasciculatim 

 congestis , uni- vel rarius plurilateralibus. Va g i ni s initio tenui- 

 bus hyalinis, aetate provecta crassis lamellosis (diametro trichomatis 

 usqve ad 4-plo latioribus), per totam latitudinem luteo-fuscis varie- 

 gatis, in filis majoribus saepius ocreatis. Trichomatibus 6,5 

 fx ad 15/* crassis, olivaceis , aerugineis vel viridibus, in pilum 

 longum hyalinum longe attenuatis. Articulis diametro trichomatis 

 2 — 5-plo brevioribus. Heterocystis forma et magnitudine varia, 

 1—4 basilaribus vel qvoqve paucis vel plurimis (usqve ad 5 seriatis) 

 intercalaribus. 



From the examination of a great number of specimens from 

 danish waters and other places it is proved that it is impossible to con- 

 sider C. scopulorum (unramified filaments , only basal heterocysts) and 



