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Show 1891.] MR. R. LYDEKKER ON A N E W MOA. 481 bone are so abraded that nothing can be gathered as to the contour of the trochlese. Approximately, it has a length of 8*5 inches and a width at the middle of the shaft of 2*1 inches, while it measures about 5 inches across the distal trochleae. In the tarso-metatarsus of Pachyornis elephantopus the corresponding dimensions are 9'4, 2*55, and 5'5 inches. The present specimen is therefore of a somewhat more slender type than the latter, but when complete appears to have had the distal trochlese somewhat more expanded in comparison with the shaft and proximal extremity. There does not appear, however, to be any well-marked character by which it can be generically separated from Pachyornis. Compared with the typical species of that genus, somewhat more important differences are shown by the femur, of which the ventral aspect is represented in Plate XXXVIII. fig. 1. It may be observed that the femora of Dinornis maximus and Pachyornis elephantopus are contrasted in the Cat. Foss. Birds Brit. Mus. p. 223, fig. 57 x; the former being characterized by its great length and slenderness and the small size of the popliteal depression, while the latter is distinguished by its shortness and stoutness and the large size of its popliteal depression, which communicates with the inner surface of the shaft by a more distinct channel, as well as by other features noticed in the work cited. Now the femur of the present bird, while agreeing with that of Pachyornis elephantopus in the contour and dimensions of the popliteal depression and in the form of the linea aspera, somewhat approximates in its general proportions to the corresponding bone of Dinornis, as is shown by the following dimensions :- Binornis maximus. Total length of femur 15-6 Distal width of femur 6*9 The present type of femur is in fact more like the corresponding bone of Anomalopteryx and Emeus. On the other hand, the femur which I have provisionally referred 'A to Pachyornis immanis has proportions much more like those of the present specimen, having a length of 14'4 and a distal width of 6*1 inches. This type of femur seems, indeed, to make it impossible to separate generically the present form from Pachyornis, to which genus I propose to refer it provisionally under the name P. rothschildi. In the work cited (p. 318) I have stated that the genus Pachyornis approaches Anomalopteryx, so far as cranial characters are concerned, much more nearly than it does to Emeus, and the present species serves to approximate Pachyornis in regard to slenderness of limb to the same genus, although the inflection of the lower end of the tibio-tarsus remains as well marked as in the type species. In the ' Catalogue ' I had very great hesitation in referring the. limb-bones mentioned under the name of Anomalopteryx (?) geranoides to the 1 In the description of this figure the scale is given as J instead of \. 1 Op. cit. p. 344. 33* New species. 10-6 4-9 Pachyornis elephantopus. 12-5 in. 6'5 in. |
