344 MR. W. K. PARKER ON THE OSTEOLOGY OF BALANICEPS REX. 
latter bird there are only two calcaneal processes behind the head of the tarso-metatarsus ; 
the external of these being the most extended parallel to the metatarsus, whilst the in- 
ternal projects furthest at right angles to the shaft. These processes in the Adjutant 
do not form a tendon-bridge, but there is a deep fossa between them. The structure 
of these parts in the Heron and in the Balzniceps is very different from that of the 
Adjutant, these birds having ecto-, meso-, and ento-calcaneal processes behind the head of 
each tarso-metatarsus. The ento-calcaneal process is by far the largest in these two 
birds, the meso-calcaneal being of intermediate size. These projections are very thick, 
and enclose two bridges or canals for tendons, besides forming two deep external grooves 
or sulci. The ento- and meso-calcaneal processes are principally formed by the middle 
metatarsal (Pl. LXVI. figs. 8 & 9 tmt), the head of which lies between and behind the 
external and internal pieces, whilst its distal end passes between and in front of the 
outer and inner coalesced portions. This distal end of the middle metatarsal 
(Pl. LXVI. figs. 10 & 11 tm#t) has a grooved articular surface for the middle toe, whilst 
the articular surfaces of the inner and outer metatarsals are simple. The small sus- 
pended innermost metatarsal bone is | inch and 2 lines long, and has a large simple 
convex articular surface for the long hallux (Pl. LX VI. fig. 1 tmt 2). In young birds the 
proximal end of the tarso-metatarsus is separate from the three long bones that after- 
wards coalesce with each other and with it; this broad thick piece of bone belongs to 
the tarsal series. 
The hallux of the Baleniceps (Pl. LXVI. fig. 1 d 2) is nearly one-third longer than 
that of the Adjutant ; and the other toes (Pl. LXVI. fig, 1d 3, 4&5) are much longer 
really, and therefore are relatively very disproportionate in size in the Baleniceps. 
The toes of the Heron are but little more than half the length of those of the Bale- 
niceps, and are only half as thick ; the actual weight of the feet of the latter bird must 
therefore be eight times as much as those of the former. This disproportionate size of 
the feet in the Baleniceps as compared with those of the Heron—the bones of the wing 
and the main leg-bones being relatively weaker in the large bird—must be considered 
when the power of flight in the two birds is compared. There is nothing particular to 
remark upon in these large, well-formed phalanges of the Baleniceps: the arching of 
the hallux and of the claw-bones and the relative length of the latter are precisely like 
what are seen in the Heron. 
The hallux of the Balzeniceps, like that of the Heron, lies in nearly as low a plane as 
the other toes ; and in the former the hinder and outer toe are very mobile; so that in 
walking the Baleniceps can turn the hallux very far inwards, and the outer toe very 
far outwards. 
In its own circle, the Baleniceps represents the Macrodactylous Rails—e. g. Fulica, 
Porphyrio, Gallinula, Parra, and perhaps Palamedea ; but a knowledge of the structure 
of this last bird is still a desideratum. 
From the feebleness of the wings and legs as compared with those of many of its con- 
