70 Palaeontologie. — Algae. 



their structure. The author points out that though the Calamites 

 are so common among the Coal Measure plants, the sections of 

 their petrified leaves are comparatively few; of those available the 

 majority were from the Lower Coal Measure horizon of the Halifax 

 Hard bed. No leaves have yet been recognised as petrifactions whieh 

 belong to the impression 'genus' Annularia. 



From their detailed anatomy, five types of leaves are distin- 

 guished by the author, but the differences are not very marked, and 

 between the more distinct types are several intermediate varieties 

 more or less connecting them. It is at present impossible to say 

 whether these differences correspond to true species or are variations 

 among leaves growing on different parts of the same trees. The 

 author considers that the most frequent type is probably that of 

 the impression species C. charaeformis. 



The detailed study of the stomata of Calamites has not hitherto 

 been undertaken, and the author establishes the fact [expected, but 

 not before demonstrated] that the guard cells were characterised by 

 transverse striations such as are seen in recent Equisetums. 



The nature of the melasmatic layer so characteristic of the 

 leaves is discussed, and it is concluded that it probably functioned 

 in the storage or conduction of the assimilation products. 



The general conclusion is that the leafy twigs probably grew 

 in a pendulous position and in a damp habitat; as they have some 

 xerophytic features a marsh or swamp forest was their probable 

 habitat. 



In their structure and origin they appear to be truly micro- 

 phyllous, no evidence resulting from the present enquiry in favour 

 of the view of a Filicinian origin of the Equisetales. 



M. C. Stopes (London). 



Camrnerloher, H., Ein Beitrag zur Algenflora der Inseln 

 Pelagosa und Porno. (Oesterr.-bot. Zeitschr. LXI. N°. 10. p. 

 373—381. N°. 111. p. 417—424. mit 12 Fig. 1911.) 



Der Hauptbestandteil der Algenflora rings um die ganze Küste 

 der Inselgruppe wird von Cystosira Montagnei J-Ag. fi moniliformis 

 Hauck gebildet. Peyssonelia rubra (Grev.) wurde auch in abnorm 

 gebildeten Exemplare gefunden. Iania adherens Lam. tritt in klei- 

 nen Rasen an Steinen auf, zumeist aber in grossen rosenroten oder 

 weisslichen Ballen an Cystosira. — Chaetomorpha aerea Kütz. trat 

 in März massenhaft auf den seichten Stellen des Ufers auf; im Juni 

 aber fand Verf. nur wenige Stücke. Matouschek (Wien). 



Cotton, A. D., On the growth of Ulva latissima in excessive 

 quantity. Botanical Report. (Royal Comm. Sewage Disp. 

 Rep. 7. App. IV. p. 121-143. 1911.) 



The report is based on an ecological stud}^ of Ulva with a 

 view to ascertaining the factors which are most important in con- 

 nection with an excessive growth of the plant in estuaries. 



The conditions of Belfast Lough are first described, where 

 a very extensive growth occurs on the mussei beds and gives rise 

 to serious nuisance on decay owing to the liberation of sulphuretted 

 hydrogen. An account is next given of the growth of the weed in 

 other localities, with different ecological conditions especially in 

 Cos. Antrim and Mayo (Ireland) and at Southampton, 



