BRITISH FOSSIL CRETACEOUS BIRDS. 509 



|- inch from within outward on the posterior side, and less on the 

 anterior side. 



Proximal end of Metatarsus. (PI. XXVII. figs. 22, 23.) 



Although many examples of the distal end of this bone have been 

 found, I have seen but one specimen of the proximal end. It has 

 been for manj'' years in the Museum of Practical Geology ; and I 

 would express my thanks to Professor Huxley for permission to study 

 its characters. 



The bone is trifid, having lost the proximal ossifications which are 

 at present usually reckoned as the distal tarsal row. The frag- 

 ment is \ inch long, and measures -i- inch in width over the articu- 

 lation, but is only two thirds as deep. At the fracture distally the 

 diameter of the almond-shaped sectiou is -| inch. 



The middle bone is entirely ankylosed with the other two. All 

 are of equal length. In front the grooves between the bones are 

 not very deep, and seem at the fracture to be disappearing. The 

 bone which is probably external has the outer side flattened and the 

 proximal end twice as long as wide. The middle bone is flattened 

 in front ; its proximal end is rather shorter. The third is half a 

 cylinder, compressed a little behind. Its proximal end is put a little 

 behind the other bones ; and it extends a little above them. 



Distal end of Metatarsus. (PI. XXVII. figs. 24, 25.) 



The distal ends are usually much broken, and rarely show the 

 articulations perfect. Occasionally the want of definition on their 

 articular surfaces may be the result of imperfect ossification. The 

 specimens show some variation in size, probably a specific character ; 

 the large one figured is from the collection of T. Jesson, Esq., F.G.S., 

 and may be referred to Enaliornis Barretti ; while the smaller and 

 less perfect examples at Cambridge seem to have belonged chiefly 

 to Enaliornis Sedgwicki. The bone presents a very close resem- 

 blance to the metatarsus of the Red-throated Diver, but is larger. 

 The several metatarsal elements in both types occupy the same 

 positions and terminate in similarly grooved pullej^-like ends, rounded 

 from front to back. 



The fragment is \+ i nc h long, and is deeply channelled in front 

 between the middle and outer metacarpal elements, as in Coh/mous; 

 but I have not been able to determine whether the groove in Ena- 

 liornis is similarly prolonged so as to perforate the metatarsus, or 

 whether a deep cleft renders the perforation unnecessary. The 

 external lateral surface is rather more inflated than in Colymbus, 

 rather more enlarged at the distal articular end, and is thrown a 

 little further backward. The two outer bones measure from side to 

 side -| inch ; they are nearly of the same length ; but the outer one 

 is slightly the longer : at the fracture proximally the diameter of 

 these elements is less than -j inch. The middle articulation mea- 



