AXIAL SKELETON OF THE OSTRICH. 401 



to exhibit a special though slight prominence (directed medianly inwards and ventrad), 

 which is the beginning of the differentiation of the catapoj^hysis^ (fig. 25, c). 



The metapophysis may be again slightly more prominent ; while the hyperapophysis 

 is so reduced that it would perhaps escape notice were it not traced from the more 

 preaxial vertebrae. 



The frezygapophysis projects beyond the parapophysis still less than in the fifth 

 vertebra, sometimes scarcely or not at all so. Its articular surface is even also relatively 

 longer and narrower than in the bone last described. 



The neural spine is excavated, both pre- and postaxially, more obliquely and ex- 

 tensively than in the fifth vertebra ; so that its median unexcavated part is relatively, 

 and may be absolutely, shorter. The lateral margins of the preaxial excavation do not 

 at all develop preaxial processes. 



Both the pre- and postaxial margins of the neural arch are rather more concave than 

 in the fifth vertebra. 



The Seventh Vertebra. 



The seventh vertebra is rather larger than the sixth vertebra, but in other respects is 

 so complete a repetition of the latter as hardly to need distinct notice except in the 

 following few points. 



The catapophyses and metapjophyses are rather more prominent; and the neural 

 spine has (at least sometimes) a greater development dorsad. 



T\ie prezygapophyses do not project forwards quite so much as do the parapophyses, 

 instead of projecting, in a greater or less degree, more preaxially, as has always been 

 the case in the vertebrae hitherto described ; their articular surfaces are directed rather 

 more inwards than are those of the sixth vertebra. 



The Eighth, Ninth, and Tenth Vertebra. 



These vertebrae slightly increase in length antero-posteriorly, though the rate of 

 increase diminishes as we proceed postaxially. In these three vertebree the catapo- 

 physial projection gradually becomes more marked ; and thereby the preaxial part of 

 the ventral surface of the centrum becomes more concave, as also the ventral marain 

 of its preaxial surface. 



The metapophyses remain as marked (fig. 28, m) or become rather more so, while the 

 hyperapophyses disappear. 



' From Kara, down. Theae processes are, as it were, merely transitional processes, sometimes merging with 

 the parapophysis dorsaUy, and sometimes with the hypapophysis ventrally. By giving them therefore a 

 distinct name I by no means wish to ignore their transition ; hut as these parts are often so distinct and 

 conspicuous as to require description and distinct reference, it is convenient to be able to speak of them 

 substantively and adjectively by a distinct term. By catapophyses I mean parts which are distinguishable 

 from, but intermediate between, parapophyses and hypapophyses, and which are placed on the ventral side of 

 the former. 



VOL. VIII. — PART VII. March, 1874. 3 L 



