344 MR. W. K. PARKER ON THE OSTEOLOGY OF BAL^NICEPS 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 Bateniceps 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 (PI. LXVI. figs. 8 & 9tmt), 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 

 (PI. LXVI. figs. 10 & 11 tmt) 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 1 inch and 2 lines long, and has a large simple 

 convex articular surface for the long hallux (PI. LXVI. 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 Balseniceps (PI. LXVI. fig. 1 d 2) is nearly one-third longer than 

 that of the Adjutant ; and the other toes (PI. LXVI. fig, 1 d 3^ 4 & 5) are much longer 

 really, and therefore are relatively very disproportionate in size in the Balseniceps. 

 The toes of the Heron are but little more than half the length of those of the Balse- 

 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 Bala^niceps 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 

 lemark upon in these large, well-formed phalanges of the Balseniceps : 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 Balseniceps, 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 Balseniceps can turn the hallux very far inwards, and the outer toe very 

 far outwards. 



In its own circle, the Balseniceps 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- 



