West^ on Diatomacece. 
151 
Mr. Thomas Atthey, of West Cramlington, along shallow sand 
ripples in Druridge Bay_, and subsequently on Cresswell Sands^ 
where it has also been observed by the Rev. Robert Taylor. 
It occurs plentiful] y^ never more than in pairs of frustules_, 
always free^ on the sands, and is, when dry, of a clear-brown 
colour. In deference to the opinion of my friend, Mr. Eoper, 
I have placed this provisionally in the genus Podosira, though 
I cannot but think it has little right to be there, and that it 
should constitute a new genus ; the compressed valves, entire 
absence of stipes or attachment of any kind during growth, 
and want of thickened umbilicus, furnishing valid grounds 
for such separation. Perhaps Coscinodiscus ? ovalis, and 
some other oval and elliptic forms, might be associated to- 
gether to form such proposed new genus. 
4. Chjetoceros, Ehr. 
C. armatum, n. sp. 
Filament compressed ; frustules quadrangular, with th6 
angles excavated, imperfectly siliceous, covered with a mu- 
cous investment ; from each angle arises a long, obtuse, curved 
seta, with some acute ones at its base ; valve elliptical ; breadth 
of long diameter, -0013" to -0032" ; of short diameter, -0005" 
to -0008". (Fig. 12.) 
Found by Mr. Glasspoole, on the Norfolk Coast, near 
Ormesby, in 1857, and communicated to me by Lieut. -Col. 
Baddeley, in the living state ; since then, abundantly on 
various parts of the coast. Filaments short, usually of six to 
ten frustules ; on one occasion only have I seen a lengthened 
filament of thirty frustules. 
Doubts have been expressed as to the true nature of this 
organism, which will be dispelled by more careful examina- 
tion; the endochrome, structure of the valves, and mode of 
increase by self- division are purely diatom aceous. As to the 
entire absence, or nearly so, of silica in its composition, I 
have long maintained that too great stress must not be laid 
on this circumstance; it would not be difficult to name 
species admitted by the most rigid systematists, which totally 
disappear on treatment with nitric acid. I am glad to find 
ray views confirmed by a valued friend, from whose letter 
the following remarks are quoted, expressing as they do so 
nearly my own views. 
He says, " I have never altered my opinion that eventually 
the disposition and colour of the endochrome will be found 
the true way of solving to what species or varieties diatoms 
belong, and not alone the markings on their siliceous enve- 
lopes, as at present held. I believe further, that there is not 
u diatom with green endochrome^ and also that we insist too 
