(1.) FIRST OR NORTH ATLANTIC PROVINCE: _Europe and the Eastern United States, from the Arctic Regions to 30° north latitude._ Balanus tintinnabulum (1 to 5). tulipiformis* confined to Europe. calceolus Europe and India. { confined to North America and West galeatus* { Indies. spongicola (2) and West Indies (?). { confined to Europe, but possibly in the perforatus* { West Indies. amphitrite (1 to 5). eburneus* { confined to North America and West { Indies. improvisus Europe and North America and (3). porcatus* Europe and North America. crenatus " " W. Indies and (2). balanoides* " " Hameri* " " Acasta spongites Europe and (2). cyathus* Madeira and West Indies. { confined to Europe, but ranges as far at Pyrgoma anglicum* { least as the Cape de Verde Islands. Xenobalanus globicipitis* confined to Europe. Chthamalus stellatus Europe and North America and (3 and 4). Pachylasma giganteum* confined to Europe. Verruca Strömia Europe and Red Sea. Spengleri* Madeira. Pœcilasma aurantia* " crassa* " Dichelaspis Lowei* " Oxynaspis celata* " Alepas minuta* Europe. parasita* Europe and Atlantic Ocean. Anelasma squalicola* Europe. Alcippe lampas* " Scalpellum vulgare* " Pollicipes cornucopia* " Here we have 31 species, of which 22 are not found in any other great region of the world. (2.) SUB-PROVINCE: _Africa, South of lat. 30°._ Balanus tintinnabulum (1 to 5). Capensis* spongicola (1) and West Indies (?). amphitrite (1 to 5). crenatus (1) and West Indies. Acasta spongites (1). Tetraclita serrata* rosea (4). Chthamalus dentatus* also on West Coast of Africa. Octomeris angulosa* Scalpellum ornatum* In this small region we have only 11 species, of which five are peculiar: _Balanus Capensis_ and _Tetraclita serrata_, seem to be representatives of _B. psittacus_ of S. America and of _T. porosa_ of that and several other regions. (3.) SECOND PROVINCE: _West Coast of South and North America, from Tierra del Fuego to Behring's Straits._