PEOFESSOK OWEN ON THE GENUS DINORNIS. 367 



the head being turned rather forward as well as projecting inward; the axis of the head 

 and neck also slightly inclines upward. The head forms more than a hemisphere. 

 From the neck (d), or constriction, the bone rapidly expands to the great trochanter 

 (f) and shaft. The articular surface is continued from the head upon the anterior 

 two thirds of the upper part of the trochanter (PI. LXI. fig. 2, c), and is defined 

 by a linear boundary from the non-articular part. Three surfaces may be noted in 

 the enormous trochanterian enlargement of this femur — the upper (epitrochanterian) 

 subdivided as above, the anterior, and the postero-external. 



The anterior, or " pretrochanterian," surface (PL LX. fig. i,g) is bisected by a low 

 linear ridge (h), which, rising about an inch below the angular summit, passes down- 

 ward and inward, and subsides (at h') on the inner side of the shaft above the expansion 

 of the inner condyle. 



The pre- meets the post-trochanterian tract at an acute angle (i) ; the latter surface 

 is traversed vertically by a rough, broad tract, commencing about an inch from the 

 summit of the trochanter, and gradually approaching the anterior angle as it descends, 

 below which the ridge bends forward, and terminates in the ectotrochanterian tube- 

 rosity (PI. LX. fig. 1, /)• 



The rough tract defines a narrow ectotrochanterian surface from the broader post- 

 trochanterian surface (PI. LXI. fig. 1, m). On this surface are two rough oval shallow 

 depressions for muscular insertions ; the upper one (PL LXL fig. 1, n, for the " abductor 

 femoris") is 10 lines below the epitrochanterian ridge, and measures 15 lines by 

 10 lines: half an inch below and rather in advance of this is the second depression, of 

 rather smaller size, but with a more irregular surface (ib. ib. o, for the " quadratus 

 femoris"). From this surface several longitudinal striae descend vertically, and are 

 continued by one principal linear ridge down the outer side of the shaft to within an 

 inch of the ectocondylar fossa (ib. k'}. A rough tract is continued from the lower 

 gluteal surface obliquely downward and backward, contracting to the strongly marked 

 ridge (PL LXI. fig. 1,^). To this ridge converges an inner less prominent oblique 

 ridge (ib. q) commencing at the inner side of the shaft, one inch below the neck. The 

 two oblique ridges are divided by a smooth interspace 4 lines in breadth, below 

 which is the orifice of the medullary artery (ib. ;•). On each side of this orifice the 

 linese asperce are, as it were, resumed, and descend slightly diverging, — the outer one 

 (ib. p') gradually subsiding near the ectocondylar pit (k) ; the inner one (ib. q') descends 

 an inch and a half below the arterial orifice to form the tuberosity, q'. Internal to 

 this rises a second rough tuberosity (ib. q"), continued by a ridge to within an inch of 

 the hind angle of the inner condyle (ib. u). 



From the ectotrochanterian tuberosity (PL LX. fig. 1, 1) the strong ridge bisecting 

 the fore part of the mid third of the shaft is continued down near the mid line of that 

 surface. Six inches below the upper end of the femur this ridge, which divided the 

 attachments of the "vastus externus" and "vastus internus" muscles, bifurcates, its 



