210 Messrs, G. M. Mathews and Tom Iredale: 



but more slender, and I feel confirmed in the opinion that 

 the two species are referable to one and the same g^enns, 

 although, for the sake of consistency, I now follow 

 Dr. Sharpe in referring the latter to the genns Nesolhnnas." 

 When Dr. Andrews introduced the genus Xesolinuiofi he 

 was writing about the '^ Extinct Birds of the Chatham 

 Islands,^' and there advocated the theory of parallelism of 

 evolution to account for the similarity of the Chatham 

 Islands (extinct) Diaphoroaptenjx to the Mauritian 

 Aphana-pteryx. It may be of interest to here note some 

 facts which seem to confirm the theory of convergence 

 wiih regard to these Rails which have or are developing 

 flightlessness. 



The present form is descended from a species of RaJIus, 

 such as Rallus pectoralis, and, in addition to its flightless 

 wings, the bill has become longer and more curved. The 

 bird from Auckland Islands, Rallus muelleri, is an inter- 

 mediate stage, not so advanced as Cabalus modestus, \n\t 

 still noticeably differing from Rallus pectoralis in structure, 

 tliough it closely resembles it in coloration. The other 

 Chatham Island Kail, Nesol'imnas dicffenhachii, which Bullcr 

 would associate with C. modestus on account of the carved 

 bill, retains in a marked degree the coloration of Hypotienidia 

 philippensis, and there can be little doubt that it is derived • 

 from a near relation of that species. The curved bill is 

 quite like that of the last-named, while the Macquarie Island 

 Rail is in an intermediate stage, the bill in that form being 

 slightly more curved than in the New Zealand race of 

 H. philippensis. It should be noted that this race (//. p. 

 assimilis) is characterised by its longer bill and degenerate 

 wing-formation. The bills of Nesolimnas and Cabalus are, 

 in our opinion, of different origin, but we hope to have more 

 to say regarding these degenerate Rails later. 



Genus IIYPOT.EXIDIA. 



Hypoteenidia Reiehenbach, Nat. Syst. Yogel, 1852, p. xxiii. 

 Type (by original designation): H. philippensis (Linne). 



