AND OTHEE EXTINCT BIEDS OF MAURITIUS. 297 



British Museum (and the restored drawings by Professor Owen in the Trans. Zool. Soc. 

 vi. and vii.), which is faulty, and upon the Cambridge skeleton, which was incomplete. 

 Hence all the references to the number of vertebrae and ribs are also at fault {cf. 

 Fuerbringer's ' Untersuchungen fiir Morphologie und Systematik der Vogel,' tabb. xxi. 

 & xxii. pp. 778-781 ; and Bronn's ' Thier-Keich, Vogel,' p. 950). 



The vertebrae examined by us belong to an unknown number of individuals. More- 

 over, it is not possible to pick out a complete series from the atlas to the pelvis, which 

 without doubt belonged to one and the same individual. Lastly, it is a curious mishap 

 that only a single specimen has been found of that vertebra which fits into the gap 

 between the last of the three anchylosed thoracic vertebrae and the first vertebra which 

 is overlapped by and fused with the pelvis. 



The determination of the number of vertebrae composing the various regions of the 

 vertebral column has consequently to rest upon circumstantial evidence. An unbiased 

 collection of facts from other Pigeons reveals certain correlations of number and shape 

 of vertebrae and ribs, and the results thus gained can be applied to the restoration of 

 the Dodo's skeleton with a considerable amount of probability. 



It seems to be the rule in normal (not domesticated) Pigeons that : — 



1. The 15th, 16th, and 17th vertebrae are anchylosed together. 



2. The 18th vertebra is free, articulating in front with the 17th, and behind with 

 the 19th vertebra, which latter in all cases is overlapped by, and partly fused with, 

 the pelvis. For the sake of convenience the 18th may be called the intermediate 

 vertebra. 



3. The 14th and 13th vertebrae each possess a spinous process which is hook- 

 shaped. 



4. Complete ribs, i. e. such as articulate with the sternum, vary from 3 to 4 in 

 number, and are restricted to the 15th to 19th vertebrae, while the 16th to 18th always 

 carry complete sternal ribs. 



5. Cervico-dorsal vertebrae are those which carry movable short ribs ; the dorsal 

 portion of such a rib articulates by a typical capitulum and tuberculum with one 

 vertebra, while the ventral or distal half of the rib is lost. As a rule, at least, the last 

 of these short ribs carries an uncinate process. The number of cervico-dorsal vertebrae 

 is two, rarely three. 



6. The other neck-vertebrae are true cervical vertebrae ; with the exception of the 

 atlas and the epistropheus, they all possess a transverse foramen and immovable rib- 

 rudiments. 



7. In recent Pigeons the last or hindmost pair of complete sternal ribs is frequently 

 followed by one pair of ribs which, attached to the 19th, or 1st pelvic, vertebra, 

 almost reaches the sternum : in rare cases there is present even a second, although 

 much shorter pair, which then belongs to the 2nd pelvic or 20th vertebra. 



The following Table will show these modifications : — 

 VOL. xm. — PAKT VII. No. 3. — August, l^^^i. 2x 



