V.—The Limbs of Lystrosaurus

Extract

Lystrosaurus, Cope = Ptychognathus, Owen (non Stimpson), has long been known from isolated but often perfectly preserved skulls. Quite recently the reception of a magnificent skeleton by the Albany Museum, Grahamstown, enabled me to give a restoration of the animal. In this drawing the hand and foot were drawn from incomplete non-associated remains. Whilst travelling in South Africa, with the aid of a grant from the Percy Sladen Trustees, I collected on the farm Klip-kuil a fragmentary skeleton of Lystrosaurus, much of which was so rotten that it could not be preserved, but which included a complete left fore-limb. This was developed by myself and was found to lie in its natural position with the digits very strongly flexed, except that the metacarpals were slightly separated laterally. It is represented in Text-fig. 1, with the humerus, radius, and ulna in the position in which they were found, and with the fingers extended. The humerus is not very well preserved, but agrees exactly with the excellent example figured by Owen, Catalogue of South African Fossil Reptiles. It is of the usual Anomodont type, with a very powerful deltoid crest extending half-way down the shaft, and a much expanded lower end with a large entepicondyle. There is a large entepicondylar foramen,