Geological Society. 255 



as in the number of incisors, the fossil resembles Didelphys ; and 

 in structure both canines and incisors resemble those of carnivorous 

 mammals. 



The left humenis is 10| inches long, but is abraded at both 

 extremities. It presents characters in the ridges for muscular 

 attachment, in the provision for the rotation of the forearm, and in 

 the presence of a strong bony bridge tor the protection of the main 

 artery and nerve of the forearm during the action of the muscles, 

 whicli resemble those occurring in carnivorous mammals, and espe- 

 cially in the FeUdae, although these peculiarities are associated 

 with others having no mammalian resemblances. The author dis- 

 cusses these characters in detail, and indicates that there is in the 

 probably Triasajc lacustrine deposits of South Africa a whole group 

 of genera {Gcdesauncs, Cynochampsa, Lycosanrus, Tiyrisuchus, Cyno- 

 S'lchiis, jyythos(nm(s, ScaJojJosaitrKS, Procolojihon, Goryonops, and 

 t'ynodracon), many of them represented by more than one species, 

 all carnivorous, and presenting more or less mammalian analogies, 

 for which he proposes to form a distinct order under the name of 

 Theriodontia, having: — the dentition of carnivorous type ; the incisors 

 defined by position, and d'vided from the molars by a large laniari- 

 form canine on each side of both jaws, the lower canine crossing in 

 front of the upper ; no cctoptcrygoids ; the humerus with an 

 entepieond}lar foramen ; and the digital formula of the fore foot, 

 2, a, 3, 3, 3 phalanges. 



The author further discussed in some detail the remarkable re- 

 semblances presented by these early EeptQcs, in some parts of their 

 organization, to Mammals, and referred to the broad questions 

 opened out by their consideration. He inquired whether the 

 transference of structures from the Eeptilian to the Mammalian 

 type has been a seeming one, due to accidental coincidence in species 

 independently created, or whether it was real, consequent on the 

 incoming of species by secondary law. In any case the lost Rep- 

 tilian structures dealt with in the present paper are now manifested 

 by quadrupeds with a higher condition of cerebral, circulatory, 

 respiratory, and tegumentary systems, the acquisition of Avhich, the 

 author thought, is not intelligible on either the Lamarckian or the 

 Darwinian hypothesis. 



" On the Occurrence of the Genus Astrocrinites (Austin) in the 

 Scotch Carboniferous Limestone Series, with the Description of a 

 New Species (-4.? Benniei), and Remarks on the Genus." By 11. 

 Ethcridgo, Esq., jun., F.G.S. 



The author, in the introduction to this paper, commenced with a 

 general history of the genus Astrocrinites of Austin, commenting 

 upon the change of name it had received from the several authors 

 who had written upon and noticed the species A. tetrayonus of Austin. 



In 1843 IMajor T. Austin described this aberrant Echinoderm under 

 the name Astrocrinites, assigning as its geological horizon the Car- 

 boniferous Limestone, and locality Yorkshire. 



Dr. H. G. Bronn rejected the name Astrocrinites on account of 



