524 ~ PROFESSOR OWEN ON THE 
‘‘calcaneal process ;” but it does not form the whole upper end or head of the middle 
piece or metatarsal element. 
In my Memoir on Dinornis, part 1 (18435"), I entered, with a view to determine the 
composition and processes of the metatarsal bone, into an analysis of its development, 
and showed, in an immature Ostrich”, that the head of the middle of the three normal 
metatarsals, which middle bone may be reckoned as that of the third digit, if the 
rudimental metatarsus of the back toe be viewed as the innermost or first metatarsal, 
projects posteriorly beyond those of the other two (second and fourth), and developes 
the chief and commonly sole “ calcaneal process.” I also showed that the mid meta- 
tarsal, in its descent toward the toes, changes its relative position to the others, coming 
gradually forward and developing its condyle in advance of, or in a plane somewhat 
anterior to, the condyles of the second (inner) and fourth (outermost) metatarsals. 
Messrs. Newton, in reference to the “ calcaneal process,” or the ‘“‘inner or longest” 
one in Pezophaps, state, “This process is now regarded® as the head of the third 
(anchylosed) metatarsal,” and quote Gegenbaur as their authority. I must, how- 
ever, enter my dissent from that view. ‘The process, as its name implies, is only a part 
of the head of the third or mid metatarsal. The portion of the head in advance of the 
origin of the process is wedged between the heads of the second and fourth meta- 
tarsals, and in a greater degree in Dinornis (tom. cit. pl. 28. figs. 4 & 7) than in 
Struthio (ib. fig. 2). 
In a subsequent Memoir (July 14, 1846) the upper and hinder outstanding process 
of the middle element of the compound bone is termed “ calcaneal”*, in reference to 
its functional analogy to the calcaneal fulcrum in Mammals, not to indicate homology, 
as Professor Gegenbaur appears to have believed. ‘The metatarsal element to which 
any tarsal homology might be applicable is expressly limited to the one affording 
articular cavities to the tibial trochlez, and ‘‘ which seems to represent a proximal 
epiphysis”’. 
To the three principal elements of the shaft the following names and symbols were 
applied® :—* ‘ entometatarse’ (11), ‘mesometatarse’ (111), ‘ectometatarse’ (1v)”—the 
numerals referring to the toes in the type or pentadactyle foot, which the three meta- 
tarsus elements respectively bore. 
The “calcaneal process” is not the “head” of the mesometatarse (11), but, as the 
' Trans. Zool. Soc. vol. iii. p. 240. ? Th. pl. 28. figs. 1 & 2. 
5 « Cf, Gegenbaur, Arch. fiir Anat. und Physiol. 1863, pp. 450-472; Untersuchungen zur vergleichenden 
Anatomie der Wirbelthiere (4to, Leipzig, 1864), pp. 93-108, pl. 6.” 
‘ «The posterior surface of the caleaneal process is broad, triangular, vertically grooved, and perforated at 
its base ” (loc. cit. p. 52). 
° Trans. Zool. Soc. vol. iii, p. 243 (1843); and see ib. vol. iv. pl. 45. fig. 2 (metatarsus of immature 
Dinornis crassus). 
® Tb. vol. iv. p. 3 (1850). 
