Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/110

24 anomalous bone is certainly the astragalus, as Cuvier determined it to be, and not a part of the fibula; it will also appear, I think, that Cuvier was right, from a morphological point of view, when he dedeclared the tibia to be laterally compressed, and that there is no proof, but rather a presumption the other way, as to the plantigrade character of Lælaps. Finally, I shall bring forward evidence to show that the structure of the tibia and astragalus in question obtained in all the genera mentioned, so that the groups of Orthopoda and Goniopoda must be disestablished.

Prof. Cope gave an account of the extinct reptiles which approached the birds. "He said that their approximation appeared to be at two points, the first by the Pterosauria, to which the modified bird Archæopteryx presented points of affinity. The second, and one not less striking, is by the Dinosauria of the orders Goniopoda and Symphopoda. He showed the essential differences between the ordinary Dinosauria and the birds to consist in the distinct tarsal bones in two series, the anteriorly directed pubes, and the presence of teeth, of the first class. In the genus Lælaps (Cope), type of the Goniopoda, the proximal series of the tarsal bones was principally represented by one large astragaloid piece, which had a very extensive motion on those of the second series. This was immovably bound to and embraced the tibia, and was perhaps continuous with the fibula, much resembling the structure of the foot of the chick of the ninth day, as given by Gegenbaur. The zygomatic arch was of a very light description. He was convinced that the most bird-like of the tracks of the Connecticut sandstone were made by a nearly allied genus, the Bathygnathus (Leidy). These creatures, no doubt, assumed a more or less erect position, and the weight of the viscera &c. was supported by the slender and dense pubic bones, which were to some extent analogous to the marsupial bones of implacental Mammalia, though probably not homologous with them.

"He said he was satisfied that the so-called clavicles of Iguanodon and other Dinosauria were pubes, having a position similar to those of the Crocodilia—also that a species of Lælaps had been observed in France, by Cuvier, which was different from the L. aquilungius, and which he proposed should be called Lælaps gallicus.

"Compsognathus (Wagner), type of the Symphopoda, expressed the characters of the latter in the entire union of the tibia and fibula with the first series of tarsal bones—a feature formerly supposed to belong to the class Aves alone, until pointed out by Gregenbaur. This genus also offered an approach to birds in the transverse direction of the pubes (unless this be due to distortion in the specimen figured by Wagner), their position being intermediate between the position in most reptiles and in birds. Other bird-like