A New Microscope

My new microscope, which is a Henry Crouch, was recently purchased at the excellent camera shop of Mr Palmer of Bridport Dorset ( Near the bus station). I have improved the fine focus with a new adjustment and I have purchased an alternative low power objective lens of Voigtlaender & sohn A G 38mm (Euryscop), for my little Foraminiferids. The Boxed microscope also contained the standard pair of objective lenses in brass cylinders with data. The Number of the microscope is 8801 and I wonder if anyone has a book containing data such as the age of this instrument. I really would be obliged for this information. brian.darnton@googlemail.com

Slide of Poole Foraminifera with labelled grid of 12

The slide was created on a standard 3 inch by 1 inch glass slide.
The artwork was first completed on a computer and the printout was reduced by photography with a 35mm camera using litho-film. The 19mm round film was gummed to a slide using uv cured glass bond after treatment . The coverslip was also stuck with glass bond.
The main species are included from the harbours` southern shore.

The Fleet Lagoon near Weymouth Dorset U.K.

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  This photo shows the shallowness of this part of the fleet. The image was taken at low tide.
  Please click on the image for a larger version. The Light coloured deposits can be seen on the aerial maps of the area as seen on the web. Live Maps may be used by either searching or clicking. See link below.

http://maps.live.com/

The red dots outline the very rich and extensive deposition sites. The species found are very similar to those of the estuarine sites of Dorset like Poole Harbour, but the arenaceous types are less numerous than at Poole.
The Village of East Fleet with its literary connections and ancient churches is an enchanting place. There are fossil types here but floatation has been used to reject them.

This is a photo of the water surface during the last stage of floatation, using material from East Fleet. It is a rich collection.

A General Guide to the Deposition Zones of the Foraminifera.

In the British Isles the tidal flows are from the SW Corner along the the South Coast. On the diagram this would be right to left, so the place to search is point B. This is valid for Swanage, Weymouth and Tor Bay. If the bays of the North East are examined then the flow is from the North Eastern corner of Scotland and on the diagram would be left to right and the site would be at A. This is valid for Scarborough and Filey. A quick look at the tide tables of ports either side of the bay in question, will soon determine direction if there is doubt. Of course few bays follow the exact symmetry of a diagram so a little common sense is required. Do not forget that blog images can be enlarged by a click of the mouse. In estuarine conditions like Poole Harbour,limited deposition zones can be identified by the concentration of shelly remains in the mud. Please see earlier posts. BD.

A glance at some of the non Arenaceous types at poole

This list is just a snapshot and by no means a complete listing.

Another look at species at Poole

These are some of the Arenaceous types, from the gastropod deposition site at Redland, Poole Harbour.

A deposition zone for Arenaceous types

In the open sea, the deposition sites in sheltered bays are pretty obvious ( see early blogs)but within the estuarine conditions of Poole Harbour do these exist? These gastropod shells seem to collect along with shelly mud in the middle tide marks of the harbour and the sievings (0.1mm-0.9mm)from this material are quite rich in arenaceous as well as other foraminifera. I have washed and sieved out the shells so that identification is possible. They are somewhat larger than 10mm. Click on the image for an enlarged version.

A species of foraminifera that does not seem to belong here?

NB Please click to enlarge most images BD

These are two images of a species that is found the year round in Swanage Bay U.K.at the deposition zone (see relevant post). The first upper image is from a test dry mounted. The lip is usually slightly more reflexed and the length is on average 300 microns though larger ones occur. It is not numerous but with each collection there are one or two tests. The lower image is from a test in Canada Balsam and in dark field illumination to reveal the hidden chambers. There is a large mega primary chamber and six or so in biserial formation. I can not find this in listings of recent Forams of the British Isles in the main text books. The only similar species is in the Brady plates Plate 75 fig 22 Siphogenerina raphanus in the Robert Wynn Jones version. The illustrated species comes from the Pacific Ocean. Since it does not seem to belong to the UK fauna , there is the possibility of it being fossil but I always float the washed and dried gatherings and fossils usually have some form of heavy inclusions. Since Swanage lies between Jurassic and Cretaceous rocks the fossil possibility I suppose exists. If anyone can point me towards a more correct name I would be obliged. For a larger picture please click on the image.

brian.darnton@googlemail.com

Dated March 2009

I have had no comments to date. but will add the folllowing information

Siphogenerina raphanus
After really long term searching I am more certain that species, which consistently turns up daily in floatings from
Swanage is part of our recent foram fauna of the Dorset Coast.

It is not listed by Murray in his 1971 Atlas nor by J.R. Haynes in his 1973 work on Cardigan Bay. The identification came
from the Robert Wynn-Jones Brady Plates revival of 1994 where there is an original image from the Brady Books on Plate 75 fig 21a &b and 22. There is no mention of the British Channel but later I found it in Cushmans Atlantic 1923 at least. Plate 42 fig14. Its a very poor drawing indeed but his text is helpful.

Generic Synonyms from Cushman.
Uvigerina, several refs to Sagrina as well as 3 references to Siphogenerina.
Some features:
Up to 1mm long. ---It begins life as a biserial test but half way becomes mono.-The costae are continuous not being broken at the sutures. There is a description of the flaring lip which I would call slightly reflexed. It is certainly distinctive enough not to be confused by S dimorpha although this near species has been recorded in the British Isles and Norway in a very positive manner.