314 



JOHS b6ye peterskn 



to more northcMii rcj^ions. The s|)ecies has, howevcr. now Ijcen lound 

 in Italy, nav cven in Iropical regions, e. {». al Singa|)ore and on Koh 

 Chanj^. Hence it niay be considcrcd as a seltled faet Ihat no delinile 

 rliniatic limils eau be slaled wilh rej^ard lo tiiis s])ecies. 



5. mainillosnm iias been foiind submersed as well as on moisl rocks 

 aniong mossos and the like. This is also the case on thc Icclandic localilies. 



V. RIVULARIACEÆ. 



I. Calothrix Agardh. 



Calothrix clavata Wesl. 



West 1914 p. 1019. 1)1. XXI, figs. 6—7. 



E. Icel. Hvalnes, in a mucilaf^inous mass, si)rin{^ near 

 high-water mark ^^js 1894 >H. J.;! 

 Area: S. Am. 



West's descriplion of this species, which lo my know- 

 ledge has been found only by the aulhor, agrees exaclly 

 wilh the s])ecimens which I found in the sample from 

 Hvalnes. The onh' dillcrencc a])pcars in Ihc basal helero- 

 cyst which in West's Jigurc apparenlly is of the same dia- 

 meter as the lower part of Ihe thread, whereas ils dia- 

 meter in the Icelandic sjiccimens is considerably smaller. 

 The thread here was 6—9 /< in diam. at the ulmost, 

 whereas Ihe heterocyst was but about 4 // in diam. lig. 17). 

 West does not mention anything as to the relation of the 

 sheath to chlor-zinc-iodine. The shealhs of the Icelandic 

 sj)ecimens assumed a deej) violet whcn Irealed wilh Ihis 

 reagent. In this we possibly i)ossess an imporlanl cha- 

 racter bj' means of which C. clavata can be dislinguished 

 from C. minnsciila Weber-van Bosse (1913 p. 42) which 

 olherwise seems lo be closely rclaled lo tlie former. 



It does not appear dislinctly from Wests slalemenls 

 (I. c.) whclher this s|)ecies was found in fresh or in 

 salt waler. Ils Icelandic occurrencc seems lo indicalc 



Fie. 17. Culo- ^'^'*t ^^ "^^y ^^ caj^able of enduring salt-water spray. 



thrix clavata II grew here in comjiany wilh Noslor sp. and Nodiilaria 



West (X()00i. Ilaroeijana. 



Calothrix epiphytica W. el d. S. West. 

 .iourn. of 15()l. vol. 35, 1897 p. 240. 



Ilvcravellir, lemp. 38^ C. W'csl 1902 p. 243). 

 Area: luir., Afr., Am., .\nlnrclic. 



This species, v^'hich I have nol seen, has been found on widely 

 differing localilies in Iropical as well as in vcry cold antarctic regions. 

 Thus it is evidenlly not an aclual Ihermal alga. bul it must be cajjable 



