Studies on the free-living protozoan fauna of estuaries in the coastal zone of Tamil Nadu, India Author Bindu, L. text Records of the Zoological Survey of India 2021 121 1 61 75 journal article 10.26515/rzsi/v121/i1/2021/141506 2581-8686 13186453 8. Arcella hemisphaerica Perty, 1852 Material examined : Mi-197, 4 ex. , Arasalar estuary, 07.xii.2013 ; Mi-207, 2 ex. , Arasalar estuary , 08.xii.2013 ; Mi-213, 3ex. , Coleron estuary , 08.xii.2013 ; Mi-232, 3 ex. , Pulicat lake , 04.xii.2013 ; Mi-263, 2 ex. , Vettar estuary , 20.vii.2014 . Diagnosis : Shell brown and slightly oval in apertural view; hemispherical in lateral view; shell surface having slight depressions; aperture invaginated and bordered by a lip; more than 2 nuclei present; diameter of test 42-90 µm; aperture diameter 15 to 20 µm. Distribution in India : Assam , Andhra Pradesh , Manipur , Odisha , Tamil Nadu (present record), West Bengal .