LARVAL FORMS, LARVA

young independent stages which differ in e ential structure from their adult form. Some are well known, (e.g.) the caterpillar and chrysalis stages of the butterfly, and many insects exhibit this two-staged youth, while most show modifications of this cycle, a quiescent period, or at least a period of moulting, preceding the attainment of adult characters. It is among aquatic and especially marine organisms, however, that larval forms are most common and most diverse. Among such groups as Coelenterates, Echinoderms, Worms, Arthropods, Molluscs, and among the and Amphibians—all or any of the members reach adult life by indirect routes through larval bypaths.: