THE DIATOMS OF GUERNSEY. 281 



unnecessary for me to do more than say a word or two about 

 the Diatoms of this island as a preface to the list of species 

 which follows. 



The only published paper bearing upon this subject, or at 

 any rate the most reliable one, is to be found in Ansted's 

 Channel Islands, second edition, p. 193. It consists of a 

 catalogue of the Diatoms occurring in a very fine series of 

 gatherings made in Guernsey during the years 1858 and 1859 

 by Dr. Wallich, and submitted for identification to the well- 

 known accomplished diatomist, Mr. T. G. Rylands, of War- 

 rington. The list is supplemented by some valuable notes and 

 suggestions from the pen of Mr. Rylands, who concludes his 

 paper in these words : " It would be difficult to name a locality 

 more likely to reward with success a diligent search for these 

 things in their natural haunts than the shores of Guernsey, or 

 in general to point to a more desirable field for the collection 

 of Diatomacece than the Channel Islands." 



In a few cases localities for the rarer forms are specified 

 in the paper quoted, but as a rule no indication is given of the 

 comparative frequency of each species or its range within our 

 area. If this had been done it would have been of the great- 

 est value to us as local botanists, for our aim should be not 

 simply to ascertain what plants occur in our little island, but 

 whether they are common or rare or local, because much 

 depends upon this in the future study of the influences and 

 circumstances which have determined the existing conditions 

 of plant distribution. 



My own researches among the Diatoms of Guernsey, 

 carried on in a rather desultory manner for several years, have 

 not been sufficiently exhaustive to enable me to make out 

 anything approaching a complete list; a large number of 

 Dr. Wallich's rarer forms have never occurred in my gather- 

 ings, though I have been able to add nearly one hundred 

 species to his catalogue ; but it seems to me that the whole of 

 the material now collected together is sufficient to warrant the 

 compiling of a provisional list which will at any rate serve as 

 a basis for further work. Localities will be specified for all 

 my own finds, and where the bare nam'e only of a species is 

 given it is to be understood as signifying that the record rests 

 on the authority of Mr. Rylands, who examined Dr. Wallich's 

 Guernsey collections. 



Rock scrapings and the washings of corallines from 

 extreme low water mark will be found as a rule very produc- 

 tive on this coast, though occasionally in certain places the 

 results are somewhat disappointing. A single gathering which 



