Ultrastructural observations of periostracum formation and shell regeneration were carried out for the lingulid brachiopod Glottidia pyramidata. The periostracum is triple-layered, and its principal ...
RECENT examination by phase-contrast microscopy of teased, fresh or macerated radial nerve, or of frozen sections in Diadema antillarum, has shown the presence of reddish cells that are neither ...