ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 475 



Setchell also treats of the species grouped by Griggs under his recently 

 established genus Renfreivia. R. parvula Griggs is identical with 

 L. ephemera Setchell. Setchell states in detail his reasons for regarding 

 Renfreivia as not separable from Laminaria, and as not being a primitive 

 form of Laminaria, but as a later form modified by environment. 

 Setchell next discusses the fructification of Pterygophora, and its 

 relationships which he thinks to be with Alaria rather than with 

 Laminaria. The unknown species Alaria marginata of Postels and 

 Ruprecht seems to be identical with A. prcelonga and A. laticosta of 

 Kjellman. Setchell also treats of some other species of Alaria, etc. 



Scytothamnus australis.* — C. M. Gibson writes on the morphology 

 and systematic position of Scytothamnus australis. She gives a short 

 history of the plant, and then describes the mature thallus, which is 

 composed of three zones, the thallus being solid, and not hollow. Hairs 

 were found on all parts of the thallus, having no connection whatever 

 with the reproductive organs. They were traced by the author from the 

 earliest stages, close to the apex of the thallus. An examination of the 

 growing point showed that the apex is occupied by a group of 

 meristematic cells and not by a definite apical cell. The apex is always 

 blunt. Sporangia are only found on plants in which growth in length 

 has ceased and the tissues are quite mature right up to 'the apex. They 

 are unilocular only, occur all over the surface, and are formed from 

 modified cells of the limiting layer. Stages in the development of the 

 sporangia are described and figured. Scytothamnus lies between 

 Dictyosiphonacese and Chordariacea? as regards the mature vegetative 

 structure. It agrees with the former in the" position and structure of its 

 sporangia, but differs from it in the lack of an apical cell. The author 

 shows that Scytothamnus australis is quite distinct from Dictyosiphon 

 fasciculatus, and that S. rugulosus is also a good species. 



Algal Blight on Tea.| — C. M. Hutchinson gives an account 

 of Cephaleuros virescens, the " red rust " of tea, an alga belonging to 

 the Chlorolepideas group. It does much damage to the tea crops of 

 North-east India, and, it is said, to mango-trees in Bengal. It attacks 

 the leaves and stems of the former and the stems of the latter. It settles 

 in crevices of young plants and forms yellow patches, and pierces the 

 tissues. It is propagated by means of water-borne zoospores and of 

 air-borne sporangia. 



Structure of Diatoms.J—W. Bally discusses the gelatinous substance 

 which is found surrounding the girdle of certain marine plankton 

 diatoms, notably species of CJmtoceras. He describes the neutral results 

 obtained by staining both fresh and preserved material, and makes 

 suggestions as to the origin and nature of the substance observed ; and 

 he thinks it consists most probably of gelatinous matter which has 

 exuded between the girdle and the valve. Minute investigation has 

 shown the author that only one, and that the older, of the "two valves 



* Joum. Bot., xlvi. (190S) pp. 137-41 (2 pis.). 



t Mem. Depart. Agric. India (Bot.) i. No. 6 (1907) 35 pp. (8 pis.). 



J Ber. Deutsch. Bot. Gesell., xxvia. (190S) pp. 147-51. 



