QUANTITATIVE ANALYSIS OF ONTOGENY OF AN UPPER ORDOVICIAN TRINUCLEID MARROLITHUS FROM ARMORICA,FRANCE

摘要

1 INTRODUCTIONUp to now,data on isolated trinucleid instars have been published (Whittington,1957；Whittard,1955,1956,1958；Dean,1960,1966；Hughes,1971) and very full descriptions of the ontogeny of Cryptolithus tesselatus Green,1832 and Tretaspis sagenosus Whittington,1959 have been described by Whittington (1959).The whole literature on trinucleid ontogeny has been well established by Hughes et al.(1975).