DIATOMACEAE. 325 
DIATOMACEAE. 
WE are indebted to a well-known Diatomist, Mr. Thomas G. 
Rylands, of Warrington, for the excellent catalogue of Diatoms, 
comprising nearly 250 species, which is given in Ansted’s Channel 
Islands, ed. 2 (1865), p. 193. Mr. Rylands states that this catalogue 
was prepared ‘from the valuable series of gatherings made at 
Guernsey in 1858-59 by Dr. Wallich. .... All the species ob- 
served, about the names of which there could be no reasonable 
doubt, have been included: but there remain others which, in the 
present state of our knowledge, can be referred with safety to no 
recorded character, and several which, there can be little doubt, are 
entirely new.’ 
In the course of some rather desultory researches among these 
microscopic plants (chiefly, it must be confessed, with the object of 
adding to my collection) I discovered a good many additions to 
this list, besides ascertaining something about the comparative 
frequency of many species: and this afforded material for my paper 
in the Zransactions of the Guernsey Society of Natural Science for 
1893. But a large number of Wallich’s species did not occur in my 
gatherings; so that only the bare fact of their occurrence in the 
island (¢estz Rylands) can at present be recorded. 
The classification here followed is that of Rabenhorst’s //ora 
Europaea Algarum (1864-68); but it has been thought advisable 
not to alter the nomenclature, especially as Mr. Rylands expressly 
states that ‘ Professor Gregory’s species are named separately, simply 
to show which forms occur.’ 
The number of Diatoms now recorded for Guernsey amounts to 
323 Species. 
MELOSIREAE. 
Cyclotella Dallasiana, Sm. 
Hyalodiscus cervinus, Grey. 
This species is marked with a query in Mr. Rylands’ list. 
Coscinodiscus centralis, Ehr. 
Coscinodiscus Oculus-Iridis, Ehr. 
Coscinodiscus concinnus, Sm. 
Cobo: frequent in rock scrapings from Jow-water mark. Moulin 
Huet, a few scattered valves. 
