myriapod: general term for any terrestrial arthropod having an elongated body composed of many similar segments: e.g. centipedes and millipedes
arthropod: invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin
macrocephaly: an abnormally large head; differs from hydrocephalus because there is no increased intracranial pressure and the overgrowth is symmetrical