Ostracode Processing Ostracode processing consisted of washing the samples through a stack of sieves (8-inch diameter standard brass sieves) of 20, 100 and 230 mesh openings (850, 150 and 63 micrometers, respectively).  Most species land on the 100 mesh (150 micrometer) sieve.  These were decanted into Whirlpak® bags, frozen, and then freeze-dried.  Freeze-dried samples were then examined under the microscope, and species with visceral mass and appendages were picked and considered as "live" specimens.  Freeze-drying is a good way of preserving specimens:  even delicate swimming appendages and pigments are preserved.  The freeze-dried samples were then stored in labeled vials. Water Sample Processing Water samples were processed and analyzed at the U.S. Geological Survey Lab in Denver, Colorado, U.S.A., with the exception of a group of samples from Smith (1991), processed at the University of Minnesota Lab, Minneapolis, Minnesota, U.S.A., and a set from Ohio sites (Smith (1992) processed by Heidelberg Water Quality lab in Tiffin, Ohio, U.S.A.  Ion balances were calculated for all samples, and the error in the ion balances for the majority of samples does not exceed 10%, although there are very dilute water samples with much higher errors. Species Identification Identification of species was done with the aid of the published literature (see reference section in this document).  Species identification was based primarily on shell morphology.  All species identifications have been double checked by at least two and sometimes by all 3 ostracodologists involved in this project (Forester, Smith, Curry).  Imaging The best examples of each species were carefully selected for imaging.  Selected shells were briefly soaked in a water bath with a small amount of bleach, rinsed, dried and immersed in distilled water for the imaging process.  A few species do not yet have an image posted on the web page, and this is simply becuase suitably pristine shells have not yet been selected.  These images will be added in the near future.  Imaging was done with a Sony® 3 CCD Color Video camera mounted on a Wild-Heerbrugg® M3Z binocular light microscope.  Images were captured using Wang's Imaging for Windows 95®, and Corel PhotoPaint 7® was used to adjust the contrast and improve clarity.