MR. W. K. PARKER ON THE OSTEOLOGY OF BAL^NICEPS REX. 323 



This table of the numerical relations of the vertebral columns of certain birds, several 

 of which birds are related to Balaniceps, will be referred to more than once in the descrip- 

 tion of this part of the skeleton. The great difficulty has been in enumerating the sacral 

 vertebrae ; but much care has been taken to examine sections and immature specimens ; 

 and where these have not been obtainable, the twin nerve-outlets on each side have 

 been carefully counted. In some cases a doubt has been expressed ; and in others, 

 rather than err, we have left out the number in that column. The most important 

 birds for comparison with the Balaeniceps are those Grallse which have short but 

 compressed bodies, or short, stout, robust bodies, with only five pairs of thoracic hsema- 

 pophyses, the last pair of which may reach the sternum, as in the Ciconies, the Balse- 

 niceps having the same structure, or may be floating and imperfect, as in Ardea and 

 Cancroma. The latter birds, as well as those of the genera Aramus, Scopus, Botaurus, 

 Nycterodius, Erodius, and Balaniceps, have the chest flat, or comiJressed, whilst the 

 Ciconice and Mycterics have a round full-shaped body. In the more distantly-related 

 Cranes, and in the still more unrelated Gallinules, Rails, and Coots, the thorax is long 

 as well as compressed, the compression being greatest in the latter group. 



Flat compressed bodies are the rule amongst the Grallte, the Rallidse carrying that 

 character to its extreme condition, whilst most of the Palmipeds have broad depressed 

 bodies. The extreme of this opposite character occurs in the genera Podiceps and 

 Colymbus. 



We see by the above table that the Balaeniceps has the same number of vertebrae in 

 the entire spine as the Heron, three more than the Boat-bill, one more than the 

 Adjutant, and two more than the White Stork. The diminution of the number of 

 vertebrae in the Boat-bill is explained by its being a small and comparatively feeble 

 form of the same type ; for, other things being equal, a large bird has a greater number 

 of vertebrae than its smaller congeners ; and small birds, generally, have relatively 

 shorter spines than large ones — the neck and sacrum being the parts in which this 

 diminution most takes place. A glance at the table makes this clear, although the 

 instances are but few ; yet they could have been multiplied indefinitely. However, it is 

 worth while to remember that the little Humming-bird has only thirty-four vertebrae in 

 all ; the Swift (best of fliers) only thirty-six ; whilst the Emeu has fifty-seven. It is not 

 intended to say here- that the three last-mentioned birds are in the least congeneric ; 

 yet the rule will be found to hold good, as a general principle, in families as well as in 

 the broad class. 



Looking at the skeleton of this great Wader, we see one of the most striking instances 

 of an aberrant form, conformable in all essentials to its type, and yet having structural 

 affinities with all the families that lie in the region round about that central type. 



When the skeleton has been described, and the curious affinities of the bird, whether 

 patent, or more secret, have been shown, then perhaps some attempt will be made to 

 prove that the Balaeniceps is only one amongst many wanderers from typical restraint, 

 and that all these aberrants are still ' under law.' 



