I am grateful to the National Science Foundation, Office of Antarctic Programs for allowing me to examine the material and for financial support (Order No. SIP 8–9459) during the writing of this paper. I also wish to thank Dr D. L. Pawson and Mr A. N. Baker for constructive criticism and assistance, and Mr M. D. King for his care with the photographs. I am also grateful to Mrs G. Spence for typing the script.