about 200 right valves of Cytherella cf. ovata Roemer, were selected from a single sample of Cenomanian age (northeastern Algeria). The material can be subdivided into two parallel ontogenetic series which were quantitatively investigated by linear regression and eigenshape analysis. The corresponding growth stages of the two series are differentiated by size, growth rate, and, to a lesser extent, by shape. The relationship between the two series are discussed mainly in terms of seasonal variation in the environment.
- Received March 1, 1989.
- Revision received October 1, 1989.
- © 1990 The Micropalaeontological Society