PROFESSOR OWEN ON THE GENUS DINORNIS. 375 
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 (Iv) 
and middle (111) trochlew, as at fig. 2, h, Pl. XLIV., and in vol. iv. pl. 3. fig. 5, Apt. otidi- 
formis. Now, this orifice is not present in one of three metatarsi of Apt. otidiformis, 
nor in one of the two metatarsi of Apt. defossor. Neither the vertical nor the fore-and- 
aft canal is present in Dinornis: I have once seen the latter canal, as an exception, in 
Apteryz. 
At the back part of the shaft Aptornis defossor shows a perforate calcaneal process 
(Pl. XLIV. figs. 2, 5, ¢), relatively longer vertically than in Apt. otidiformis: the ridge 
on the inner side of each side-wall (fig. 4), indicating the portions of the canal traversed 
respectively by the tibialis posticus (e’) and the “flexor longus digitorum ” (e), is better 
marked, and the bony canal is less contracted posteriorly, than in Apt. otidiformis. The 
postinternal longitudinal crest is shorter and more produced in Apt. defossor; the fossa 
internal to its upper part, for the origin of the “flexor brevis hallucis,” is well defined, 
as is the surface below the crest for the attachment of the metatarsal of the hallux 
(fig. 2,1). The longer surface at the outer and back part of the metatarsal for the 
insertion of part of the strong gastrocnemial sheath-like tendon is strongly marked. 
Every thing bespeaks the force with which this massive metatarsal was worked in 
Aptornis. 'The proportions and disposition of the distal trochlee in Apt. otidiformis 
(fig. 5) are closely repeated in the larger species (fig. 1,@); the inner one (fig. 2, 11) 
does not terminate at a higher level than the outer one (ib. Iv); the cleft between the 
outer and middle trochlez is deeper and anteriorly wider than the inner cleft, in both 
species of Aptornis. The outer trochlea in Dinornis (fig. 8, 1v) is shorter than the inner 
one (ib. 11). 
To exemplify the generic, or family, or ordinal distinction between Aptornis and 
Dinornis, I take the present opportunity to figure the metatarsus of the species coming 
nearest to Aptornis in size’, viz. D. curtus (Pl. XLIV. figs. 7-10), first indicated by the 
mutilated bone described and figured in Zool. Trans. vol. iii. p. 325, pl. 48. fig. 6. 
The metatarsus of Aptornis defossor, above described, formed part of the extensive 
series of remains brought by Mr. Walter Mantell from Ruamoa, Middle Island of New 
Zealand, and purchased by the British Museum in 1856 (Trans. Zool. Soe. vol. iv. 
pp- 149, 156). Deeming, then, that it might prove to belong to a larger variety of the 
Aptornis otidiformis of the North Island, I concluded to wait for further evidence, 
which the bones brought from the same neighbourhood (Oamaru) by Mr. Taylor have 
now given. The tibia (Pl. XLI. fig. 9) fits this metatarsus (Pl. XLIV. fig. 1) as well as 
the tibia of Apt. otidiformis (Zool. Trans. vol. iii. pl. 25. fig. 5) fits the metatarsus 
figured i op. cit. vol. iv. pl. 3. fig. 5. 
1 Unless the small bone (Pl. XLIY. fig. 7) should indicate an established breed of that inferior size, meriting 
a distinctive name, and should not belong to a female or somewhat dwarfed individual of D. curtus. 
