Published online by Cambridge University Press: 01 May 2009
Young stages isolated from limestone from Girvan indicate that the first two thecae had unsclerotized walls but apertural rings showing that they opened downwards beside the sicula. The development can thus be matched with that of Glossograptus and the two families Glossograptidae and Cryptograptidae merged. The recognition of downward-opening thecae in C. tricornis allows the earlier species C. schaeferi to be more easily accommodated in the genus. Relationships in the family are reviewed.