OSTEOLOGY OF THE DODO. 65 



to gain thickness at the under part of the neck and at the lower and back part of the 

 trochanter, the compact wall acquiring a thickness of a line at the beginning of the 

 shaft, where the cancellous structure is confined to the outer side of the pneumatic 

 cavity ; this structure gives way to a few deUcate filaments of bone crossing the cavity 

 of the major part of the shaft, and is not resumed until the bone expands to form the 

 distal condyles (ib. fig. 7). 



The five tiUm of Bidus in the same collection range in length from 8 inches 8 lines 

 to 9 inches. The procnemial ridge (PI. XXII. figs. 1, 2, 4, p) is a triangular plate, 

 with the base longest and the apex rounded ofi": it inclines outwardly, and does not 

 extend much more than half an inch from the level of the proximal end of the bone : 

 the length of its base rather exceeds an inch : on its inner side a triangular muscular 

 sui-face is well defined by an irregular inferior line or ridge (ib. fig. 2, n). The ectocnemial 

 process (ib. figs. 1, 3, 4, e) is thicker, shorter, and terminates roughly and obtusely. 

 There is a low, narrow ridge (ib. fig. 2, g), about half an inch in length, on the inner 

 side of the proximal end of the shaft, beginning about 9 lines below the articular sur- 

 face at that end. The fibular ridge (ib. figs. 1 & 3, h), beginning 1 inch 8 lines from 

 the proximal end, extends about 2 inches down the outer side of the shaft. The epi- 

 cnemial ridge (ib. figs. 1 & 4, ^) is obtuse, and but little produced above the upper 

 articular surfaces or condyles {t d) of the tibia : the breadth of that end of the bone, 

 in the longest specimen, is 2 inches 3 Imes. The tendinal canal at the fore part of 

 the distal end is bridged by bone (ib. fig. 1, I), and is situated on the inner half of that 

 aspect of the shaft ; the lower opening is subcircular and close to the anterior end of the 

 inner lower condyle (ib. «), which is more produced forward than the outer one (ib. b). 

 Their hind ends project very little beyond the level of that aspect of the shaft of the 

 tibia. An intermuscular ridge (ib. fig. 1, r) strengthens into a tuberosity (;•') at the inner 

 side of the tendinal groove. 



The cancellous structure in the tibia is limited to an extent of about half an inch 

 below the proximal articular surfaces (PL XXIII. fig. 8), and to about an inch and a 

 half from the distal end of the line (ib. fig. 9) : the shaft is occupied by a large air-cavity, 

 with a compact wall of half a line in thickness at the upper third, gradually increasing 

 to about a line at the lower fourth, until the cancellous structure is reestablished ; the 

 transverse direction of a plate of this structm-e indicates the extent of the original 

 distal epiphysis of the tibia (fig. 8). 



The fibula (PI. XXII. figs. 6-8) presents the usual ornithic characters of the bone : 

 it varies from 4 inches 4 lines to 4 inches 6 lines in length, with a greatest jiroximal 

 breadth of 8 lines. No adequate gain would result fi-om a detailed description or com- 

 parison of this bone ; and the rest of the bones of the foot have received eveiy requisite 

 attention in this way in the excellent work on the Dodo and its kindred, already 

 quoted. A longitudinal section of the vietcfarsus, taken in the direction from side to side 

 (PI. XXIII. fig. 10), shows the loose cancellous texture of the common epiphysis of 



VOL. VI. — PAKT II. K 



