208 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 20, 



of each condyle. The posterior trochlear surface is very slightly 

 concave transversely. The sides of the condyles are almost flat. 

 The bridge is broad, transverse, submedian : the canal is narrow, 

 with the lower outlet oblique and close to the inner condyle. 



Order Galling. 



In the Curassow (Crax Alector) the breadth and depth of the 

 condyles are equal ; their anterior convexities slope gradually to the 

 intercondyloid space, which has a small well-marked pit at its lower 

 part ; the sides of the condyles are very shallow, the outer ligamentous 

 tubercle is slightly marked. The bridge is a little to the inner side 

 of the mid-line, and is very broad, subtransverse ; with the lower 

 outlet oblique, and close above the inner condyle. 



In the Cock {Phasianus gallus) the condyloid convexities are 

 more distinct, or relieved from the intercondyloid space, than in the 

 Curassow {Crax), and the fossa in that space is less marked : — in 

 other respects the same characters prevail. 



In the Turkey {Meleagris gallopavo, fig. 6) the relative breadth 

 of the distal end of the tibia is rather greater ; it has a relatively 

 narrower bridge and a wider canal than in the Cock ; the bridge is 

 rather nearer the mid-line ; external to the bridge is a low tubercle, 

 just above the outer condyle : a narrow and shallow canal divides the 

 bridge from the tubercle ; the fossa, at the bottom of the intercon- 

 dyloid space, is well-marked. In other respects the tibia of the 

 Turkey closely resembles that of the Cock. 



Order Grall^. 



In the Bustard {Otis tarda, fig. 7) the breadth and depth of the 

 distal end are subequal : the condyles slope to a very narrow inter- 

 space : they are equal, but the innermost is most prominent, and 

 most convex. The bridge, on the inner half of the bone, is broad, 

 subtransverse, supporting a transverse ridge, which bounds above the 

 cavity into which the lower outlet of the canal opens. The posterior 

 part of the trochlear surface is deeper, its borders being more pro- 

 duced and sharper than in the Turkey and other GalUncB. The 

 ectocondyloid surface is slightly concave, with a median tubercle ; 

 the entocondyloid surface is more concave, with a larger tubercle 

 near the anterior end of the inner condyle. The groove leading to 

 the bridge has a ridge on the inner side, but none on the outer side 

 of the bone. 



In the Adjutant Crane {Ciconia argala) the depth exceeds the 

 breadth of the lower end of the tibia more than in any other bird : 

 the condyles are equal ; the interspace is very short and narrow ; 

 that space is represented by the deep cavity formed by the tubercle 

 and ridge developed from the bridge above, and by the oblique con- 

 verging upper borders of the condyles below. The bridge is very 

 broad, internal ; the lower outlet is round, looks obliquety down- 

 wards and forwards, and opens into the supracondyloid concavity two 



