Note 555 — Chapter XII · THE SPIRAL SHELLS OF THE FORAMINIFERA

A difficulty arises in the case of forms (like Peneroplis) where the young shell appears to be more complex than the old, the first formed portion being closely coiled while the later additions become straight and simple: “die biformen Arten verhalten sich, kurz gesagt. gerade umgekehrt als man nach dem biogenetischen Grundgesetz erwarten sollte,” Rhumbler, op. cit., p. 33 etc.