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part of the shaft, toward the outer side; a second linear ridge, commencing lower 
down, runs along the back of the shaft towards the inner side as far as the popliteal 
space; between these ridges, near halfway down the bone, opens the canal of the 
medullary artery. The distal end is less expanded than in Aptornis or Cnemiornis. 
The rotular channel, thongh wide, is relatively deeper and narrower than in Aptornis, 
and the inner border is more produced. A small tuberosity projects external to the 
upper end of the outer border: this may be individual. The popliteal space shows no 
definite fossa, and its surface is irregular. The fibular articular groove is deeper, with 
a better-defined and produced outer border, As in the thigh-bone of the Rallide 
generally, there is no pneumatic foramen. 
§ 7. Metatarsus of Aptornis defossor. 
In general form and proportions this bone resembles that in Aptornis otidiformis: 
the superiority of size is shown in the “Table of Admeasurements,” and in figs. 1-4, 
Pl. LXXXVII. As compared with Dinornis (ib. figs, 7-10), the metatarsal of Aptornis 
defossor shows the same greater depth and nearer equality of size of the two condylar 
cavities (ib. fig. 4), with the broader and loftier intercondylar tract, as in Apt. ofid?- 
formis' (ib. fig. 6), the same superior prominence and perforation of the calcaneal process 
(ib. figs. 2-4, ¢, c'), the same flattening of the back part of the shaft through the non- 
projection there of the upper half of the mid metatarsal element, also the presence of the 
canal (ib. ¢) for the tendon of the “ adductor digiti externi.” The inner (entotibial) con- 
dylar cavity is on a rather higher level than the outer (ectotibial) one, is rather deeper, 
rather less from before backward. ‘The cavity at the upper part of the front surface 
of the metatarsal shaft is relatively less deep than in Aptornis otidiformis ; it is not con- 
tinned so low down upon the shaft; but the anterior outlets of the interosseous canals 
open separately at its bottom, and the ridge at the inner border for the insertion of the 
corresponding part of the tendon of the * tibialis anticus "is strongly marked and defined. 
In Dinornis the interosseous canals converge from behind forward to a common orifice 
(0, fig. 7) at the bottom of the shallow upper and anterior depression. In one specimen 
of metatarsus of Aptornis defossor the groove (¢, fig. 1) for the tendon of the “ adductor 
digiti externi” deepens as it approaches the interspace between the middle and outer 
digital trochlew, and perforates the bone above that interspace; in another it deeply 
grooves the interspace, but is not crossed by the bony bridge at the fore part. of the 
interspace. A similar variety is shown by one of three specimens of metatarsis in Apt. 
otidiformis. Where the bridge exists, the tendinal canal opens in the interval or chink 
between the two trochlee; but there is commonly another canal, continued from the 
% adductor groove,” which traverses the bone backward and opens into the lower con- 
cavity of the posterior surface of the metatarsal above the interval between the outer (ty) 
and middle (ut) trochlew, as at fig. 2, h, PI. LXXXVIL., and in vol. iv. pl. 3. fig. 5, Ap#. 
» P, 200. 
