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Diversity
 The Gault is noted for its diversity, Wilkinson (In Bristow, 1990) has recorded 69 species and subspecies in boreholes in East Anglia, while at Folkestone, the author has obtained 40 species in total. There is little variation in diversity, taking into account first appearances and local extinctions: near the base are 16-17 species, above bed III the diversity rises to 20 species and remains constant, then gradually rises from bed VII to bed IX to give 24 species.

Preservation.
 The preservation of the Ostracoda within the Gault Clay facies is exceptional. With careful preparation, exquisite specimens may be obtained with fine internal details such as the marginal pore canals, hingement and muscle scars clearly visible to aid in identification. The valves are often translucent, showing little signs of recrystallisation. It is apparent that little post-mortem transport or abrasion took place before burial, since specimens may be found with a full complement of external spines. Occasionally pyritised specimens may be found, but generally they do not show as much detail.

Stratigraphic Distribution.
 There are two levels where small faunal turnovers occur. Firstly, there are local extinctions of Clithrocytheridea nana and Orthonotocythere cf. fordensis Kaye, 1965 and the first local appearance of Cytherelloideachapmani (Jones & Hinde, 1890) in bed II, followed by the first local appearances of Phodeucytheretrigonalis (Jones 7 Hinde, 1890) and Isocythereisfortinodisreticulata Gründel, 1964a near the base of bed III. A little higher in bed III are first appearances of Rehacythereisluermannae (Triebel, 1940) and Bythoceratinaumbonata (Williamson, 1848). The assemblages remain quite stable until the second faunal turnover at the level of the cristatum nodule bed. Here, in bed VIII, just above the Middle/Upper Albian boundary are found the local extinctions of Cytherelloideachapmani, and Protocytherealbae Damotte & Grosdidier, 1963, accompanied by the appearance of minor components Eucytheruramultituberculata Gründel 1964, Eucytherura cf. nuda Kaye, 1964a and Patellacythere sp.. Just above, in the base of bed IX, are the first appearances of Cytherelloideastricta (Jones & Hinde, 1890), Cytheropteron nanissimumnanissimum Damotte & Grosdidier, 1963 and Bythoceratinaumbonatoides (Kaye, 1964).

History of Study.
 The first published work on British Cretaceous Ostracoda (Jones, 1849), included specimens from the Gault Clay at Folkestone, the "Chalk Detritus" of Charing in Kent and from the Gault of Leacon Hill, near to Charing. Moore (1878) listed 12 ostracods from the Gault in Meux’s Well, London, while Price (1879) listed 14 species from the Gault of Folkestone; Jones & Hinde (1890) updated the taxonomy of earlier works within their monograph. They also list Ostracoda from the Gault at Folkestone from the collections of Chapman, also the Gault of Godstone from the collections of Chapman and Sherborne.
 The Gault at Folkestone was examined systematically for the first time by Chapman & Sherborn (1893), who recorded fifty-four species, eight as new, and related their occurrence and abundance to the bed numbers of Price (1874, 1875). No further work on the British Gault Clay ostracods was carried out until Kaye (1964) revised, redescribed and re-illustrated the marine Cretaceous fauna in the light of new taxonomic advances. A detailed study of the Gault fauna was undertaken by Kaye (1965) and this contains much information on the distribution of new species from twenty-nine localities across England. He also published on the Lower Cretaceous Ostracoda from the Gault equivalent Speeton Clay faunas in Yorkshire (Kaye, 1963, 1963a, 1963b, 1963c,1965a).
 More recent work has been carried out on the Gault of East Anglia and Eastern England (Wilkinson & Morter, 1981; Wilkinson, 1988, 1990) which unlike the early taxonomic work, concentrated on biostratigraphical aspects of the ostracod faunas. The most comprehensive species list is that given by Wilkinson (In Bristow, 1990) where 69 species are presented in a stratigraphical chart of the Gault from two boreholes near Thetford, which range from the dentatus to the dispar ammonite Zones.
 In continental Europe the Albian has been examined for its ostracod content by Triebel (1938, 1938a, 1940), Mertens (1956), Damotte & Grosdidier (1963), Bertram & Kemper (1971), Kemper (1971, 1984, 1989), van der Wiel (1978), and Damotte (1979, 1979a). Middle and Upper Albian and Cenomanian faunas were described by Witte et al. (1992) from the eastern part of the Netherlands. Other works which are useful for identification of Albian Ostracoda are Neale (1978) and Babinot et al. (1985). A review of mid Cretaceous Ostracoda of Europe was undertaken by Damotte et al. (1981).

Ecology
 The distribution of ostracod species are influenced by various physical parameters including salinity, temperature, pH, oxygen concentration, depth, substrate and food supply. Salinity is the main control, and very different assemblages are obtained in marine, brackish and freshwater environments. The ostracods found in the Gault clay are all fully marine species. Water temperature tends to restrict the geographical distribution of ostracod species; at Folkestone there are many species in common with those found in the Gault of northern France, north-western Germany and eastern Holland, but very few in common with southern France or northern Spain. Abundance of Platycopida has been associated with lowered oxygen conditions on the sea floor (Whatley, 1991), their success being attributed to the ability to circulate more water as a consequence of their being filter feeders. However, in the Gault, platycopid ostracods, while being common, are not dominant.

Collection and preparation
 Micropalaeontological sample collection differs from normal fossil collecting, because it is not usually possible to tell if your sample contains any microfossils until after some further preparation work has been carried out. For serious collecting, it is necessary to be able to identify the exact horizon from which a sample has been taken, with reference to published lithological logs. Usually a suite of samples is taken at a predetermined vertical interval; for a reconnaissance survey, for example, every 1m is sufficient. During any micropalaeontological work, it is necessary to be aware of contamination from material other than that of the sample of interest. So, at the rock face, remove the loose surface debris and weathered rock until fresh material is exposed and excavate a block of approximately 1kg, then bag, label and record the sample.
 Retain half of the block for reference and process half for microfossils. For clays such as the Gault Clay, a simple method will suffice to extract both ostracods and foraminifera. Brake the clay is into centimetre sized pieces, and dry in an oven at about 40OC, for a few days. Then immerse the clay in plenty of water with an added water softener, like Calgon, or washing soda, and allow to soak for up to week. The clay should break down into a soupy mixture, boiling often helps the breakdown.
 To recover the ostracods from the liquid, a combination of decanting and sieving may be used. To collect most of the juvenile instars and smaller species of ostracod, such as the Cytheruridae, a 63?m or 125?m sieve is used. The residue obtained on a larger mesh, of 250?m, is easier to pick through, but will only contain the larger juvenile and adult specimens of the larger species. Often, after drying, it can be helpful to re-wet, boil and sieve for a second time, which removes the last of the clay and cleans the specimens thoroughly. A successful processing will reduce 0.5kg of rock to about 2g of residue.
 Dry the sieved residue in a low oven, then bottle and label ready for picking. Picking is best done on a low power binocular microscope with magnifications of x10 or x20. Scatter the residue thinly onto a flat tray, and systematically examine each grain for microfossils. Extract any specimens with a moistened 0000 sable hair brush, and set down on a glued 32 cell assemblage slide for further examination.

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