328 MR. W. K. PARKER ON THE OSTEOLOGY OF BALAZNICEPS REX. 
cellularity of the bone, and these lower vertebra gradually increase in width; so that 
the seventeenth is more than 14 inch across the diapophyses, the ninth being only 1% 
wide at the same part. In the two last cervicals the upper articular surface for the 
‘tubercle’ of the rib is flat, that for the round smooth ‘ head’ is rather deeply concave, 
as in the dorsal vertebre. 
The formation of the carotid ‘ hemal’ canal in the neck of birds is exceedingly inter- 
esting, but its anatomy is not a little obscure. In 1844 Professor Owen’ taught that 
these were typical vertebre ; but this mistake was soon corrected by him, and the true 
nature of these canals as productions of the centrum (in a part of the body of the bird 
where there are only very small rudiments of ribs and no hemapophyses or hemal 
spines) was shown. ‘To the writer’s mind, the distinction between parapophyses and 
hypapophyses is faulty, dividing as it does parts that are essentially one in signification. 
In his masterly memoir the ‘ Croonian Lecture?,’ Professor Huxley has shown the great 
uniformity and simplicity of the structure of the vertebral column in all the Vertebrata, 
and to his views our own have for a long time been approximating. But many a passage 
from Professor Owen’s most invaluable works might be brought to show that these struc- 
tures are far more simple and uniform than would appear from their nomenclature. 
In Professor Owen’s Report ‘On the Archetype and Homologies,’ read at the Meet- 
ing of the British Association held at Southampton in 1846, we have the following 
remarks (page 254 of the General Report) :— 
‘In the Sturgeons (Sturio, Polyodon) the inner layer of the fibrous capsule of the 
gelatinous notochord has increased in thickness, and assumed the texture of tough 
hyaline cartilage. In the outer layer are developed distinct, firm, and opake cartilages, 
the neurapophyses, which consist of two superimposed pieces on each side, the basal 
portion bounding the neural canal, the apical portion, the parallel canal filled by fibrous 
elastic ligament and adipose tissue ; above this is the single cartilaginous neural spine. 
The parapophyses are now distinctly developed, and joined together by a continuous 
expanded base, forming an inverted arch beneath the notochord for the vascular trunks, 
even in the abdomen. Pleurapophyses are articulated by ligament to the ends of the 
laterally projecting parapophyses in the first twelve or twenty abdominal vertebre ; in 
‘the anterior ones those ‘ vertebral ribs’ are composed of two or three distinct cartilages. 
The posterior pleurapophyses are short and simple. The parapophyses gradually bend 
down to form hzmal arches in the tail, at the end of which we find hemal cartilaginous 
spines corresponding to the neural spines above.”’ And again in page 255 :—“ In the 
osseous fishes I find that the centrum is usually ossified from six points, four of which 
commence, as Rathke describes, in the bases of the two neurapophyses and the two 
parapophyses ; but the terminal concave plates of the centrum are separately ossified *. 
They coalesce with the intermediate part of the centrum, which is sometimes completely 
' See his Lectures on Comp. Anat., vol. ii. p. 44. ? Delivered at the Royal Society, June 17, 1858. 
3 Vogt, Williamson, and Huxley speak of this annular ‘ diapophysis’ as being ossified from only one centre. 
