PROFESSOR OWEN ON THE GENUS DINORNIS. 253 



indicated by a single small foramen (fig. 1, rf). The hallucial surface (fig. 2, y) is 

 barely definable. Along the distal half of the fore surface of the bone the mid meta- 

 tarsal shows a recognizable prominence. The distal end of the bone closely adheres to 

 the dinornithic type ; the depressions ii', iv', figs. 3, 4, are well marked ; the condyles 

 II, III, IV have the usual dinornithic proportions and relative positions. The digits 

 n, Hi, iv have the usual phalangial formulae ; the mid toe {Hi) is longer in proportion 

 to the metatarse than in Binornis robustus \ but is shorter in proportion to the digits 

 ii, iv ; the ungual phalanx of each toe is rather sharper and more decurved than in 

 the larger species. 



§ 13. Phalanges. 



For comparison of the foot-bones oi Binornis parvus with those oi Binornis rheides, 

 reference may be made to plate iii. of Memoir, part iv. Trans. Zool. Soc. vol. iv. 1851, 

 and with those of Binornis dromoides to plate ii. of the same part and volume. It 

 will be seen that the smaller species under description shows intermediate proportions 

 of the toes in regard to thickness and length. 



In the absence of any definite indication of an articular surface for the innermost 

 toe, it might have been inferred that Binornis parvus, like some larger species, to which 

 I therefore originally limited that generic appellation, had lacked that part of the foot — 

 a part which, being better developed in other species, led to their being referred to a 

 genus Palapteryx. But the degree in which the digit i (PI. LVII. figs. 8, 9) may be 

 reduced without being wholly lost, is significantly demonstrated by the subject of the 

 present ' Part,' owing to the care with which the bones of the individual, dying in the 

 cavern most probably a natural death, were collected. 



§ 14. Conclusion. 



If the skeleton of Binornis parvus (Pis. LI. & LVIII.) be compared with those of 

 B. maximus, B. robustus, B. crassus, B. rheides, D. gravis, B. didiformis, B. gracilis, 

 and B. casuarinus -, it will be seen that the smallest species (PI. LVIII. of the present 

 Part) has proportionally the largest skull. The modifications of the frame accompanying 

 augmentation of bulk in the genus, are chiefly manifested by greater proportional 

 length and strength of the terrestrial limbs. If the peculiarly nutritious roots of the 

 common ferns of New Zealand contributed, with buds, foliage, or other parts of trees, 

 to the food of the gigantic race, the concomitant gain of power in the locomotive and 

 fossorial limbs seems not to have called for a proportional growth of brain or of bill. 



' Trans. Zool. Soc. vol. iii. p. 47, pi. i. 



' 'Memoirs on the Extinct Wingless Birds of New Zealand,' 4to, vol. ii. 1878, Is. xovi., xcvii., cviii.-cxiij 



