1856.] OWEN — GASTORNIS PARISIENSIS. 205 



Director of the Scientific Instruction at the * Ecole Normale supe- 

 rieure,' of M. Lartet, the well-known and accomplished Palaeontologist 

 of the tertiary formations in middle and southern France, and of Prof. 

 Valenciennes were briefly recorded in the notice of the discovery of 

 the tibia, communicated to the Institut, in March, 1855*. In the 

 month of June in the same year M. Hebert communicated to the 

 Academy of Sciences, his discovery of the femur, at about 3 metres 

 of horizontal distance from the spot, and in the same formation, 

 where the tibia had been previously found by M. Gaston Plante. 



The femur is the shaft of that bone of the left limb, with both 

 articular ends broken away : it measures 11^ inches in length, and 

 2 inches by 1 inch 9 lines in the two diameters of its middle part. 

 The entire femur of a large male Ostrich measures 13 inches in 

 length ; and 2 inches by 1 inch 5 lines in the two diameters of its 

 middle part. 



The tibia also has its proximal end broken away and its distal 

 condyles mutilated : its length, when entire, would be 1 foot 7 inches : 

 it is 1 inch 9 lines by 1 inch 6 lines in the diameters of the middle 

 of the shaft. The tibia of a large male Ostrich measures 1 foot 

 11^ inches in length ; the diameters of the middle of the shaft being 

 1 inch 6 lines by 1 inch 3 lines. 



The femur of the Parisian eocene bird, for which the name 

 Gastornis Farisiensis has been proposed, has a rounder and thicker 

 shaft in proportion to its length than in the Ostrich, and the tibia 

 is shorter and thicker than in the Ostrich ; whence, as M. Hebert 

 rightly infers, the Gastornis was a proportionally heavier bird than 

 the Ostrich. In the size and proportions of the two above-specified 

 bones of the leg it closely corresponds with the species of Binornis 

 which I have called Binornis casuarinus (figs. 2 « & 2 5). As the 

 conclusions, in reference to the more immediate affinities of the Gast- 

 ornis, to which the above-cited able naturalists and palseontologists 

 of Paris have arrived, were founded almost exclusively on the cha- 

 racters presented by the lower or distal end of the tibia, I shall pre- 

 mise a brief summary of the leading modifications of that part of the 

 skeleton in the different orders of the class of Birds. 



Characters of Birds'' Tibice. — The tibia is a well-marked and 

 characteristic bone in birds. At the proximal end the intercondyloid 

 convexity is more marked than the entocondyloid concavity, which 

 is the principal articular surface there developed : next may be 

 noticed the strong rotular process dividing into the procnemial and 

 ectocnemial ridges f. Below and behind these is the usually short 

 fibular ridge, marking the outer side of the proximal third or fourth 

 part of the shaft. The distal end of the tibia resembles that of a 

 mammalian femur, with the back of the two condyles turned forwards. 

 All these characters, common to birds in general, distinguish this 



* Compte Rendu, Mars 12, 1855. 



t First so named and defined in my memoir on the Dinornis of June 1846, 

 Zool. Trans, vol. ill. p. 323; these ridges are not developed in the Hornbill 

 {Buceros), 



