NEMATODES FROM SKIPPERS ISLAND
205
Sample 1. Mud obtained from a pond (known as "Heronry pond")
in April, 1958. The pond probably represents an accumulation of rain
water and is inhabited by sticklebacks (Gastreosteus) and Corixa stag-
nalis (leach) (identified by Mr. R. H. Izzard). It lies above the level of
most, if not all high tides and the water is known to be only slightly
saline. Several elm trees grow round the edge of the pond which is
itself proof that the ground does not contain an appreciable quantity
of salt. However, no truly freshwater or terrestrial nematodes were found
there.
Salinity of the water taken in March, 1958: 5.6 per mille pH 8.5
(March, 1958); pH 8.7 (July, 1958). (All determinations by Dr. R. H.
Nisbet.)
Sample 2. Soil surrounding grass roots growing on the edge of
"Heronry pond" collected in July, 1958. The water level of the pond
was much higher than usual due to the abnormally high rainfall at the
time.
Sample 3. Soil soaked with brackish water from "Dragonfly ditch"
200 yards north of the workshop, collected in July, 1958.
Sample 4. Soil from a ditch, soaked with brackish water, at the rear
of the boathouse, collected in July, 1958.
Sample 5. Marine mud collected in September, 1958, from above the
dam, but below the level of low water. [Salinity determined by Dr. R. H.
Nisbet (water taken off the landing stage): 31.1-31.2 per mille (March,
1958); 30.7 per cent (July, 1958).]
Sample 6. Moist soil surrounding grass roots collected from a higher
level on the Island in September. 1958. It was found to contain a
totally different fauna—typical of a truly terrestrial habitat.
The following is a list of the species of nematodes found; all of
which have been reported previously from Europe and European
waters (see Goodey, 1951; Schuurmans Stekhoven, 1935; Gerlach, 1954).
The fact that, even in the few samples available, five of the twelve
identifiable species are new records from Britain, shows that the study
of free-living nematodes has been neglected in this country.
Adoncholaimus thaiassophygas (de Man, 1876). Found in all the
samples with the exception of the non-brackish soil (sample 6). Recently
reported from Britain (in mud at Whitstable) by Maghraby and Perkins
(1956).
Axonolaimus sp.
Sample 5 (marine mud).
Cyatholaimus sp.
Sample 5.
Dichromadora geophila (de Man, 1880).
In sample 1 (mud from the bottom of "Heronry Pond"). This species
does not appear to have been reported from Britain before.