262 THE ESSEX FIELD CI.UH. 



two stamens and from one to four ovaries, enclosed in a sheath and produced on 

 the under edge of the frond. 



"Two of the Balrachian Ranunculi are very common in the marshes. One — 

 heterop/iyllus — with a few floating' reniform leaves, with the lower one submerged, 

 multifid, with filiform segments. The oih.tr —trkophyllus — has all the leaves 

 submerged, and smaller flowers. Flowers of both are white and float on the 

 surface when expanded. These are very variable and confudng plants, no two 

 botanists being, apparently, agreed about the nomenclature. They are said to 

 be destitute of the acrid and poisonous properties of the terrestrial species — the 

 common Buttercups. 



" The above are the commonest aquatic plants which we have found in tiie 

 d3'kes and drains which intersect the marshes, and I will add a few remarks, which 

 may not be scientific, but which may possibly help the searcher after aquatic 

 moUusca and microscopic algas abounding in these ditches. E.xperience has 

 taught me, that the examination of the water weeds often affords a valuable clue 

 to the mollusca most likely to be found existing there, and they, too, also \'ary as 

 to their preference of brackish er fresh water, while others can manage to exist 

 indifferently in either. Amongst the pond-weeds previousl}' mentioned, the 

 following forms, to the best of my recollection, thrive equally well in fresh-water 

 ditches and in those that are slightly brackish : v/^., Potamogeton and Lemna minor, 

 or the Smaller Duckweed. The Ivy-leaf Duckweed (^Lemna trisulca) and the 

 American Pond-weed (^Anacharis alsinastrum) seem to favour a fresh-water 

 habitat, and in aquaria 1 have found they invariably die off if submerged in 

 water that is at all brackish. 



"An aquatic weed, abundant in the ditches inhabited by our new Hydrohia, is, I 

 believe, the Horn-wort (^Ceratophylhtm'). An Alga, which I take to be Entero- 

 morpha intestinalis, is ver}^ abundant in the marshes on both sides of the river. 



" The ditches upon the marshes are of course a favourite hunting-ground for the 

 microscopist, abounding with the following minute Algse : — Nostoc cceruleum, in 

 immense jelly-like masses; Scenedesmus -^nd, Pediastrum ; Desmidiea^ of the 

 genus Micrasterias and Cosjnarium abound, with innumerable shoals of Diatoms, 

 amongst which I have frequently noticed Pinnularia major and P. viridis ; quite 

 a number of species of Naviculcr^ Ortlwsia and Fragilaria. Spirogyra also may 

 be taken here, but, to my thinking, it is not nearly so abundant as in man)' other 

 fresh-water localities. 



" In the future, I hope to devote more time and attention to the very 

 interesting study of these aquatic plants, and particularly to the microscopic 

 algae of the Thames marshes." 



Mr. Monckton kindly read for the author, Mr. French, of Felstead, a paper 

 " On the Occurrence of Westleton Beds in parts of North-west Essex " {ante, pp. 

 210-217). Mr. Monckton made some remarks on the paper, which, together witii 

 a note from Mr. Dalton, are printed at the end of the paper (E.N., pp. 217, 218). 



Cordial votes of thanks were accorded to Mr. Monckton and to the authors of 

 the papers, and the meeting ended with the usual conversazione, at wiiich Mr. 

 Jenkins' fine collection of Mollusca was examined with much interest. 



Ordinary Meeting, Saturday, November 28th, 1891. 



The 129th Ordinary Meeting was held (by the kind permission of the Rev. 

 W. LinLon Wilson) in the hall of St. John's College, Loughton, at half-past six 

 o'clock. Prof. R. Meldola, F.R.S., Vice-President, in the chair. 



Extracts from a paper by Mr. Frencli, " On some Ancient Lake-Remains at 

 Felstead, with Notes on some similar Remains in the District," were read by tiie 

 Secretary (the full text of the paper will be published in a succeeding number of 

 the Essex Naturalist). 



Remarks upon the paper were made by Prof, McldoIa and Mr. ^V. Cole, and 

 a vole of thanks was returned to the author. 



