( 83 ) 



Diaphoraptrryx hawkins' ... 

 Aptornis defossor ... 

 Triboiif/x mortier'i ... 

 Aphamqiteryx broecki 

 Erythromachus legiiatJ 

 Ocydromus f uncus ... 

 Ciihalus nylvestris ... . . 

 Hypotaenidla celehetisis 

 Fulica atra ... 

 liallus aquaticus 



A comparison of the relative proportions of the fore and hind limbs in Diaph&r- 

 apteryx and other birds may be of some interest, and the following table shows tliis 

 approximately, the length of the leg being taken as 100 : — 



Wim:. 



D'u(phoraptery.c hawkinai ... ... ... ... 44 approx. 



Ocydromus fuacus ... ... ... ... ... 46'5 



Trihonyx mortieri ... ... ... ... ... 48 



Ei-ythromachiiti h:guatl ... ... ... ... 52 approx. 



(?) Cahalus dicffenbach/i 52 



Cabalu.i sylivslri.s 58 



Hypotarnidia celebeiisis ... ... ... ... 59'5 



Rallus uquaticus ... ... ... ... ... 64 



Fulica atra 82 



In making this calculation the length of the wing is taken as the sum of the lengths 

 of the humerus, radius, and metacarpus, because in the fossils the phalanges are 

 wanting ; since, however, these latter are gi-eatly affected in the reduction of the 

 wing, their omission tends to make difference between the wings of the flightless and 

 flying forms appear somewhat less than it really is. The length of the leg is, of 

 course, taken as the sum of the lengths of the/cm(tr, tibm, and metatarsus. 



From the foregoing description it will be seen that Diap}i,orapter}/x is merely an 

 Ocydromine rail, in which the reduction of the wings has advanced somewhat farther 

 than in the living forms, and has been accompanied by a lengthening of the beak 

 and a considerable increase in bulk. Milne-Edwards* has shown that Apjhanapterijj: 

 is likewise an Ocydromine i-ail which has undergone a similar series of modifi- 

 cations, and its similarity to DiapjliwapAeryx is so remarkably great that Forbes 

 was justified in his hesitation in according the Chatham Island bird generic 

 rank ; but the inferences he draws from the similarity of the two forms do not a]ipear 

 well founded. He considers + that their occiuTenee in ^lauritius and the Chatham 

 Islands is strong evidence that these were formerly connected with the great Antarctic 

 Continent, for the existence of which a large body of evidence has been brought 

 forward by various writers. It is true that the geological structtu-e of the Chatham 

 Islands tends to show that they form part of a continental area, since they are largely 

 formed of sedimentary deposits consisting of clay-slates, limestones, % and various 

 fossiliferous tertiary deposits, which, according to Hutton, § probably range from the 



• '■ Sur les AffinitSs Zoologiques cic l'-\phaiiaptciy.'c," Ann. Set. Nat. (5 series), Vol. X. (1868), p. ;i25. 



t " Tlie Chatham Islanrls : Their lii-latioii to a former Southern Continent," Siippletnentary Papirt of 

 the Moi/al (leuyraphieal Society, Vol. III., l'(. 4 (IS'.IS), p. 607 (with map). 



I Von Haast, " On the Eock-Sirecimens collecteil h\ H. H. Travei-s, Esi]., in the Chatham Island?, ' 

 Trans. N. Z. Instit. Vol. I. (ISGit), p. ISO (with map). 



§ Catal. Tert. .Moll, and Ecli. K Z. In Coll. Colonial Mmcitm. Introduction, p. viii. Wellington, 1^73. 



