13 
The radial carpal bone (PI. I. 56) presents a trochlear surface, concave from the radial 
to the ulnar end, convex transversely to the magnum, here confluent with the base of 
the mid metacarpal (111). The ulnar carpal (55’) is the smaller bone, and offers a deeper 
groove to the convex compressed process of the base of the fourth or ‘‘ annulus” meta- 
carpal (tv). The second or index metacarpal (11) is 6 lines long, compressed, and con- 
fluent by its whole length to that of the medius. It supports a phalanx (1), 10 lines 
long and pointed at the end, which does not quite reach that of the mid metacarpal. 
This (ib, fig. 1, 111) is 1 inch 9 lines long, inclusive of the magnum, and is confluent 
with the fourth slender metacarpal (rv) at both ends, leaving an interosseous space 
1 inch 1 line long and 2 lines wide. 
The proximal phalanx of the medius (111.1) is broader than the metacarpal, having 
its ulnar border extended into a ridge and slightly produced beyond the distal articular 
end. To thisis joined a second phalanx (ib. 2), terminating, like that of the forefinger, 
ina point. The length of the hand is 3 inches 6 lines. The broad and flattened general 
character of the bones of the fore limb relate to the support of a surface in the 
shortened wing adequate, as a fin, to strike the water with effect. 
§ 4. Pelvic Arch and Appendage. 
The pelvic arch has been described. Its appendage departs less from the general 
ornithic type than does that of the scapular arch. 
The femur (Pl. [. fig, 1,65; Pl. IL fig. 11), 2 inches 10 lines in length, shows 
the usual extension of articular cartilage from the head to the upper part of the 
ueck and great trochanter, expanding upon the latter, The ligamentum teres is im- 
planted in the upper part of the head. The trochanter does not rise to a higher level ; 
the ridge at its fore part descends about 6 lines upon the bone, gradually subsiding ; 
the back or outer side of the trochanter is broad and nearly flat; the popliteal side of 
the shaft of the proximal part is flattened, the rotular side is concave. The shaft soon 
assumes a full elliptic transverse section, is very slightly bent, with the concavity 
backward ; it slightly expands to the distal condyles. It has a large medullary cavity. 
The rotular groove is wide, and is partially defined from the intercondyloid or popliteal 
groove, in which are the depressions for the crucial ligaments. The outer condyle has 
the usual backward or popliteal production, vertically grooved for the compressed head 
of the fibula. 
The tibia (Pl. I. fig. 1, 66; Pl. Il. fig. 12) is 5 inches 2 lines in length. The 
proximal articular surface is but feebly defined; the tibial or inner division is the 
largest; the fibular division is convex. The rotular process, of a triangular form, with 
a base as broad as the tibia, rises half an inch above the articular surface, and sends off 
a procnemial (Pl, II. fig. 12, p) and an ectocnemial (e) ridge. The latter is short, 
thick, and angular ; the former is long, thin, and also forms a low angle. ‘The proximal 
part of the shaft of the tibia is trinedral: there is an oblong tuberosity on the inner or 
