416 PROF. H. G. 8EELET ON EVIDENCE OF A BIRD FROM [Aug. 1 899, 



27. On Evidence of a Bird from the Weald en Beds of Ansty Lane, 

 near Cuckfield. By Prof. H. G. Seeley, F.E.S., E.L.S., F.G.S. 

 (Read May 24th, 1899.) 



On a visit to Ansty Cross made by the London Geological Field 

 Class, I identified a fragDient of bone found embedded in the sand- 

 stone by Mr. Neville Jones, as probably the distal end of the femur 

 of a bird. It was unfortunately extracted from the matrix, and 

 subsequently it was left with me for determination. 



The fragment is | inch long, compressed from back to front, with 

 the bone of the shaft thick and enclosing a small medullary cavity. 

 At the proximal fracture the bone is | inch wide and i inch thick. 

 The width at the distal articulation is -^-^ inch ; and the bone 

 becomes bent downward and is thickened inferiorly with develop- 

 ment of the condyles, though not to quite the extent seen in most 

 existing birds. 



The inner side of the bone is narrower than the outer side. As 

 the narrow, rounded inner side of the shaft is prolonged distally, 

 it becomes flattened, with a slight median coQvexity ; and is 

 thickened, partly owing to a superior marginal ridge, and partly 

 in consequence of the thickening of the inner condyle. 



The outer side of the bone is thicker, but not so thick as in the 

 femur of Enaliornis ; nor is the external side flattened so much as 

 in that genus. An inflation on its middle part defines a superior 

 lateral oblique area, below which there is an imperfect groove. This 

 defines a thickening of the outer side of the large external condyle, 

 quite on the type of Enaliornis and Colymbus. 



The external condyle is not only larger and deeper, but is more 

 prolonged distally. This is perhaps the most ^distinctive avian 

 character ; for though in a Dinosaur the inner side of the distal end 

 may be flattened, and the outer side angular, it is the inner condyle 

 which is usually the larger. And in no case is the external condyle 

 produced distally, except apparently in Hypsilophodon, exceptionally 

 according to Hulke's figure. The condyles are well rounded. The 

 external surface of the bone, in consequence of the size of the outer 

 condyle, has the appearance of extending obliquely outward, making 

 a slight approximation to the condition seen in Colymbus and its 

 allies. 



The superior surface of the bone does not widen so rapidly at the 

 distal articulation as in Enaliornis ; but there is a similar shallow 

 groove on it which widens to the distal extremity, extending later- 

 ally over the condyles. The groove becomes prolonged into the 

 notch between the condyles on the distal extremity of the bone. 



The inferior surface of the shaft is concave in length and also 

 from side to side, being bounded laterally by slightly-developed 

 rounded ridges, which extend proximally from the condyles. The 

 notch between the condyles is narrower and deeper than in Enali- 

 ornis, owing chiefly to the well-rounded form of the condylar surfaces 

 on the under side of the bone. 



