162 Royal Society : — 



specimen then known was so incrusted with stalagmite that not 

 much could be made of it. The present remains show that it was 

 very markedly different in many respects from that of Bidus. The 

 cranium is narrower and longer, and without the peculiar frontal 

 protuberance of Didus, being nearly flat at the top, with the fore 

 and hind part elevated into two bony ridges of cancellous structure. 

 The upper mandible also presents a remarkable difference from that 

 of Didus, where the axes of the nasal process and the maxillary 

 converge, whereas in Pezophaps they diverge. The maxilla also was 

 relatively very small ; and the mandible differed by being much 

 straighter above, showing a salient angle on its lower edge (which is 

 very inconsiderable in Bidus), and being much more solid poste- 

 riorly. In the quadrate the two birds are more alike. The rest of 

 the bones of the head are wanting. 



A comparison of the entire skeleton shows that Pezophaps is in 

 some degree, and perhaps on the whole, intermediate between Didus 

 and the normal Columbse, while it has some features, such as the 

 armature of the wing, quite peculiar. It has no very near affinity to 

 Didunculus ; indeed that form must be considered the type of a 

 separate family, though not so aberrant as the Bididce, which must 

 be looked upon as the most remotely connected of the order Colum- 

 bae. Strickland was amply justified in arriving at the conclusion 

 that the Solitaire of Rodriguez was generically distinct from the 

 Dodo ; but it seems expedient to define his genus Pezophaps more 

 precisely. Accordingly the following characters are assigned to it : — 



Rostrum mediocre, curvatum, processu nasali et ramis maxillaribus 

 antice divergentibus. Frons plana, porca osseo-cancellata circum- 

 data. Ossa coracoidea robusta. Alae breves, involatiles. Manus 

 singulis bullis osseo-callosis armatse. CoUum et pedes longiores. 



In like manner the genus Bidus may be defined : — 



Rostrum magnum, aduncum, processu nasali et ramis maxillaribus 

 antice convergentibus. Frons tumida, in umbonem hypoconicum 

 osseo-cancellatum surgens. Ossa coracoidea attenuata, scapulas 

 obtuse attingentia. Alae breves, involatiles. Manus inermes. Col- 

 lum et pedes breviores. 



The account given by Leguat of his Solitaire is then quoted in 

 full, as also that of d'Heguerty, the latter from Strickland, and the 

 authors proceed to remark upon the different causes of extinction 

 of species within historic time. This, when effected by man's 

 agency, is seldom done by man's will ; and various cases are cited 

 to support this opinion. In extirpating species man generally acts 

 indirectly ; and they succumb to forces set in motion indeed by him, 

 but without a thought on his part of their effect. In the case of the 

 extinction of the Solitaire of Rodriguez, the cause usually suggested 

 seems inadequate ; and the authors consider it was probably effected 

 by feral Swine, and quote a remarkable passage from an old French 

 Voyage, showing the extraordinary abundance of these creatures in 

 Mauritius, where, in or about the year 1 708, above fifteen hundred 

 had been slain in one day. It is plain that where these abounded 



