FRESHWATER ALG.E. 



j i 



trichomatibus gradatim attenuatis, sed non in pilum productis, non 



pseudo-ramosis, inter cellulas vix constrietis, dissepimentis distinrtis ; cclluli.s ad 

 basin trichomatis tain longis (jiiain latis vel modicc dcplauatis, sursum diamctru ad 

 duplo longioribus, coiitcntu serugineo granuloso. 



Diam. HI. ad bas. = 8-9 yu, ; diain. trieh. ad bas. = 5-C> IJL ; diam. trich. in media 

 partc = 4-5 /z ; diam. hcterocyst. = 5-6 /A ; crass, parietis vagiuac = '8 p.. 



Hull. Gap pond, Winter Harbour. 



The filaments are curved and intertwined to such an extent as to make it almost 

 impossible to follow one from end to end (fig. 15^). In places these densely 

 entangled filaments form a thin stratum completely hiding the underlying Phormidium, 

 but at other points they are much more loosely arranged. The base of the sheath is 

 often a little inflated, and in this ease there is a rapid narrowing of the filament just 

 above the base ; beyond that point, however, the attenuation is very gradual, and the 

 termination of the filament is only slightly narrower than it is just above the inflated 

 base (figs. 159, 1GO). The terminal cell of the trie-home appears to be more or less 

 pointed and acute (figs. 159, 1GO). 



This species bears considerable resemblance to the Cnlothrix sp., described and 

 figured by Messrs. West ("/' Clf -, P- 298, PI. XXV., figs. 55-57), which they regard as 

 probably being a new species of the genus ; but there arc some important differences 

 vix. the subtorulose cells (which are quite different to those of C. intricata), and the 

 obtuse terminal cell of the trichomes. Possibly Messrs. West's specimens are a variety 

 of C. intricata. The genus Calothrix is, however, evidently well represented in the 

 Antarctic with a considerable number of new forms. 



There is some resemblance between C. intrifntn and (.'. epiphytica W. and 

 (i. S. ^'est, but, apart from the somewhat larger dimensions, the former differs in. 

 the fact that the trichomes do not taper into a hair and in the highly tortuous 

 character of the filaments. 



56. CALOTHRIX GRACILIS, sp. u. 



(PL III., figs. 164-17-2.) 



Filis rectis vel sa-pc modice fiexuosis, solitariis vel subgregariis, usque ad 400 fj. 

 longis, in superficie Phormidii repentibus, rare pseudo-ramosis ; vaginis tenuissimis, 

 hyalinis, an-tis, basin intcrdum iuHatis ; hetcrocystis basilaribus, et in filis lougioribus 

 ctiain intcrcalaribus, plerumque solitariis, in vaginis iuclusis, dcplanatis, hemisphsericis 

 vel rarius obconicis, membraua modice incrassata couteutu homogeneo ; trichomatibus 

 non in pilum productis, plerumque gradatim attenuatis, sed ubi basis vagina) iuflata est 

 subito attenuatis paultim supra basim, cellula apicali aruta ; trichomatibus in partc 

 basali inter cellulas modice constrictis : eellulis inferne ssepe paulo deplanatis 

 (prsesertim ubi basis fili infiata est), in media parte ct superne diametro circa l|plo 

 longioribus, contentn cum pain-is granulis ; sporis (an maturis '.} binis (semper?), 

 cylindricis, diametro l|-2plo lougioribus, membrana levi. 







us* 



