BRITISH FOSSIL CRETACEOUS BIRDS. 507 



those in which ossification is complete. In the "Woodwardian Mu- 

 seum is a similar larger proximal end of a tibia without a patella, 

 which I take to be that of Enaliornis Barretti (figs. 20, 21). There 

 are also distal ends of tibiae : the Woodwardian Museum is fortunate 

 in possessing an example of each species. 



The large proximal ends of the bone in Enaliornis Barretti are four 

 in number. Mr. Eeed's specimen is the finest. Twelve years since I 

 noticed that it was 1| inch long, with a subquadrate shaft and strong 

 compressed semiovate patelloid process fully f inch high, with flat- 

 tened subparallel surfaces. Both lateral margins of the patella 

 develop ridges which are directed outwards. The ridge on the 

 fibular side of the bone is the stronger. The shaft terminates upward 

 internal to the patella in a flattened horizontal slightly convex sur- 

 face wider than deep, though the depth is increased by projecting 

 backward over the posterior face of the shaft. This articulation for 

 the femur is nearly -i- inch wide, but is not so deep on the inner side 

 and is rather narrower towards the fibula ; the surface is slightly 

 oblique, sloping from the front backward. In front the shaft is 

 channelled ; and posteriorly it is somewhat concave from side to side. 

 It is compressed externally and develops a fibular ridge on the pos- 

 terior external margin at £ inch below the femoral articulation. 

 The internal surface of the shaft is flat. The proximal end figured 

 PI. XXVII. fig. 20 is in the collection of T. Jesson, Esq., F.G.S. 



The distal articular end of the right tibia of Enaliornis Barretti in 

 the Woodwardian Museum (PL XXVI. figs. 24, 25) has the shaft 

 much compressed from back to front, and sharp along the fibular 

 margin. The articulation is -| inch broad. The (?) tarsal element is as 

 completely ankylosed to the tibia as in most Ornithosaurs and existing 

 birds. The condyles are broad and rounded, the internal one being 

 the larger of the two. The depression between the condyles appears 

 to be less deep than usual. There is a deep channel in front on 

 the fibular side ; but it does not appear to have been arched over by a 

 bridge, but was defended by a strong process directed outward from 

 above the inner condyle. This is one of the most distinctive parts 

 of the skeleton of Enaliornis. 



The tibia of Enaliornis Seclc/wicH, like all the other bones, is 

 smaller than the tibia of the species just described. The Wood- 

 wardian fragment of a right proximal end (figs. 13, 14, 15) is 

 about 1J inch long. The shaft, where fractured at the commence- 

 ment of the fibular ridge, is triangular in section, less than -J inch 

 wide, and more than | inch deep on the slightly convex internal 

 aspect. The other surfaces of the shaft appear to be more flattened 

 than in E. Barretti, the vertical channel on the anterior surface 

 being conspicuously shallower. The proximal articulation for the 

 femur is subquadrate, more than -| inch wide, and not quite so 

 deep. The articular surface consists of a flattened internal sur- 

 face for the condyle, and a mamillate process rising above that 

 level, which extends to the outer margin of the bone, showing 

 that the external condyle of the femur was supported entirely on 

 the fibula. The patelloid process is shaped much as in the other 



