Facultad de Ciencias Exactas y Naturales, Buenos Aires and Bodenbiologisches Institut, Imst, Tirol, respectively.
The present communication has been made possible by a subsidy from the Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina We are also indebted to the Universidad Austral de Chile, Valdivia, and Dr.Klaus Kubitzki, Münster, for transportation, shelter, and advice.