104 OBSERVATIONS ON BRITISH MARINE ALGJE. 



swarming in the water, whilst the cells of those fronds which were 

 protected from sunlight by the black paper were still in the undivided 

 condition. I tried experiments with coloured papers of various 

 tints, but refrain from publishing the results of these experiments 

 until I have had, during the coming summer, an opportunity of 

 working out the subject more systematically. 



III. 



Marine 



ANTRANSIA 



Whilst examining some Callithamniea collected in Plymouth Bay 

 in the autumn of 1889, by my friend Prof. Johnson, of Dublin, I came 

 across several plants of Ceramium rubrum covered with Chantransia 

 corymbi/era Thur. On the same host plants I observed a large 

 number of small creeping plants which, owing to the fact that the 

 material was quite colourless (having been preserved in strong spirit), 

 I at first took for a species allied to Acrochate repem Pringsh. On 

 sending a specimen to Mr. E. A. L. Batters, he, however, at once 

 diagnosed the plant as young stages of Chantransia corymbifera, and 

 suggested that I should compare the young stages of this form with 

 other species of the genus. (I may remark in passing thai the adult 

 filaments bore cystocarpia, which, Mr. Batters informs me, have only 

 once before been seen in Britain, viz., by himself at Sidmouth.) 



The British species of Chantransia are, according to Holmes and 

 Batters, five in number, viz., C. Daviesii, C. corymb if era, C. virgatula, 

 C. secundata, and C. luxuriant. I have examined the young stages 

 of all of these, and made the following notes on them* The mono- 



id 



bifi 



the spore at once gives rise to creeping filaments, each terminated 

 by a long colourless trichome. Trichomata, so far as I can make 

 out, do not seem to be formed in the other species until a later 

 period. Waiving the question of the specific distinctness of C. 

 rwjatitla, C, Daviesii, and C. luxuriant (and I find it very difficult to 

 separate these from one another in certain stages of growth), it may 

 be noted that G. virgalula and C. luxurians agree in forming from the 

 spore a discoid expansion one layer thick, from almost all save the 

 marginal cells of which arise the erect branched filaments. C* 

 secundata also forms a disc by division of the spore,* but the disc is 

 more extensive, and relatively few erect filaments are at first 

 formed. C, Daviesii, on the other hand, has a more massive disc, 

 two or even three cells thick, and erect filaments arise from nearly 

 ail the cells, These four species then seem to form a series, so far 

 at least as their young stages are concerned, C. virgatula and 

 C. luxuriant having the simplest type of disc, C. Daviesii the most 

 complex and massive, with C. secundata as an intermediate type. 

 t\ corymbifera, on the other hand, does not form a disc ; the spores 

 give rise to creeping filaments, which branch and finally curve 

 upwards, each terminated by a colourless trichome, absent from 

 young filaments of other species. 



(To l>e continued.) 



* See .Murray & Burton in Journ. Linn. Soc. (Bot.), vol. xxviii. p. 212, footna 



