359 
AMPHIPRORA PALUDOSA_ W.sm. 
AS A WEST RIDING DIATOM. 
J. W. H. JOHNSON, B.Sc. 
Thornhil’. 
In November, 1909, an examination of the aquatic flora and 
fauna of a small watercourse near Wakefield revealed a sudden 
diminution in the vegetation. This diminution occurred 
immediately below the junction of a feeder carrying water 
from a colliery. 
The flora above this junction was characterised by large 
masses of Ceratophyllum demersum, Elodea canadensis, and 
quantities of filamentous alge. At this point the larger 
forms of vegetation disappeared entirely, but some distance 
below. small quantities of Enteromorpha intestinalis were 
observed, and later Cladophora glomerata occurred in quantity. 
& B E D E 
Figs. A-C, Amphiprora paludosa W. Sm., x 500, Thornhill. 
D, E, -Nitzschia clausit Hantzsch, x 1000, Alilwarke Dike. 
” 
The stream soon joins another watercourse of equal size, 
and the aquatic flora then rapidly recovers its former condition. 
Mud taken from this barren stretch yielded a few living 
specimens of the diatom Amphiprora paludosa, which appears 
to be quite new to the West Riding Flora. This diatom, which 
is recorded in Van Heurck’s ‘ Diatomacez’ as a ‘ brackish’ 
species, was not found in the upper portion of the stream. 
The occurrence of this diatom associated with Enteromorpha 
suggested the possibility of an unusual saline condition of the 
water in this area. 
Determinations of the salinity (NaCl) showed that the 
feeder contained as much as -g per cent., and that the stream 
below the junction contained -5 per cent. of this constituent, 
1g1r Oct. 1. 
