THE INTERMEDIUM IN BIRDS. 9 



Fig. 9. Side view of the distal end of tibia and tarsus of a young Blue Heron. 

 The intermedium, as in the case of the young Ostrich and young fowl, has the appearance 

 of an ascending spur from the other tarsal bones. 



DIXOSAUKIAN REPTILES. 



Fig. 10. 

 Ornithotarsus. 



Fig. 11. 

 The "Hun/leur Reptile." 



Fig. 12. 

 Laelaps. 



Fig. 10. Distal extremities of the tibia and fibula of Ornithotarsus, after Cope's figure 

 in Trans. Amer. Phil. Soc., Vol. xiv, fig. 35, page 122. The tibiale and fibulare are 

 coossified. Whether the intermedium is represented by the enlargement of the tibiale 

 in front, or was a separate bone which occupied the fossa on the anterior face of the tibia, 

 is a matter of doubt. Ornithotarsus certainly presents a number of features that warrants 

 its name. 



Fig. 11. Distal end of tibia and tarsus of the " Honfleur Reptile," reduced from a 

 figure in Cuvier's Ossemens Fossiles, described by Cuvier under the general head of 

 Megalosaurus, without identification, afterwards named by Cope Laelaps gallicus. The 

 intermedium is seen as a blunt portion ascending from the other tarsal bones. 



Fig. 12. Distal end of tibia and tarsal bones of Laelaps; side view. Reduced from 

 Cope's figure in Trans. Amer. Phil. Soc., Vol. xiv., plate 9. In this figure the intermedium 

 is again seen as a long ascending spur in front of the tibia, but the coossified tibiale and 

 fibulare occupy a far different position in relation to the distal articular face of the tibia 

 from what is seen in birds. 



WORKS REFERRED TO. 



1. On the Anomalous Relations existing between the Tibia and Fibula in certain of the Dinosauria as 

 illustrated by the genus Laelaps. Prof. Cope. Proc. Philad. Acad. of Sciences, Dec. 1866, p. 317. 



2. An Account of the Extinct Reptiles which approach the Birds. Prof. Cope. Proc. of the Philad. 

 Acad. of Sciences, Dec. 18G7, p. 234. 



3. Synopsis of the Extinct Batrachia, Reptilia and Aves of North America. Prof. Cope. Transactions 

 of the American Philosophical Society, read Sept. 18, 1808, and April 2, 1869. 



