PACHYORNIS ROTHSCHILDI LYD. _Pachyornis rothschildi_ Lydekker, P.Z.S. 1891, pp. 479-482, pl. XXXVIII. The bones in the Tring Museum, which form the type of this species, unfortunately have no history and their locality is unknown. It differs from the other species of the genus by the slenderer proportions of the tibio-tarsus, which is 22 inches long by 2.9 inches distal width, as opposed to 24 inches by 4.2 in _elephantopus_ and 20 inches by 3.5 in _ponderosus_, the two nearest in size. Femur: length 10.6 as opposed to 12.5 inches in _elephantopus_. {216} PACHYORNIS PONDEROSUS (HUTT.) _Euryapteryx ponderosus_ Hutton, Trans. N.Z. Inst., p. 137 (1892). This species is slightly smaller than _P. elephantopus_, the tarso-metatarsus varying from 8.25 to 8.0 inches, as opposed to from 9.4 to 9.25 in _elephantopus_; the tibio-tarsus varies from 18.5 to 18.6, as opposed to 24 to 24.1; femur, 10, as opposed to 13 to 11.8. The skull can be distinguished by the processes at the hinder angles of the basi-sphenoid, which are higher and rounder in _ponderosus_, flatter and more elongated in _elephantopus_. Type: Hamilton. Habitat: Middle Island, New Zealand. Cast of egg in Tring Museum, taken from specimen in Otago Museum, dredged up in 1901 in the Molyneux River, also incomplete skeleton from Kapua Swamps. PACHYORNIS INHABILIS HUTT. _Pachyornis inhabilis_ Hutton, Trans. N.Z. Inst. XXV, p. 11 (1893). Differs from _ponderosus_ by having the great inward expansion at the distal end of the tibio-tarsus. This expansion has induced some ornithologists to separate the species of _Pachyornis_ into two genera--_Euryapteryx_ and _Pachyornis_--but I do not think this expansion of sufficient importance to warrant generic separation. Habitat: Middle Island, New Zealand. PACHYORNIS VALGUS (HUTT.) _Euryapteryx valgus_ Hutton, Trans. N.Z. Inst. XXV, p. 12 (1893). This species is at once distinguishable from all others by the extraordinary internal expansion of the distal end of the tibio-tarsus. The tarso-metatarsus is 8.5 inches = 216 mm. in length and the proximal width 3.5 inches = 89 mm., and does not differ much from _crassus_ except in the great proximal width, necessary to articulate with the distal internal expansion described above. The type came from Enfield in New Zealand. Habitat: Middle Island, New Zealand. {217} PACHYORNIS PYGMAEUS (HUTT.) _Euryapteryx pygmaeus_ Hutton, Trans. N.Z. Inst. XXIV, p. 739 (1892). As implied by its name, this is the smallest species of _Pachyornis_, the tarso-metatarsus only measuring 6 inches in length. The type came from Takaka. Habitat: Middle Island, New Zealand. PACHYORNIS COMPACTA (HUTT.) _Euryapteryx compacta_ Hutton, Trans. N.Z. Inst. XXV, p. 11 (1893).