56 PROFESSOR OWEN" ON THE 



postzygapophyses (z'), converging towards the middle of the upper surface of the neural 

 arch, being arrested, save in one instance, at the sides of the ligamentous surface 

 occupying the common position of the base of the neui-al spine. 



In the axis vertebra (PI. XVII. figs. 12 & 13) the posterior articular surface, concave 

 vertically, and 3 lines in that extent at its middle part, is very convex transversely, being 

 continued upon the sides of the posterior part of the centrum ; a thick obtuse hyp- 

 apophysis (fig. lS,/>ij) descends below this surface: the anterior or odontoid surface 

 presents the usual form in bhds; the odontoid process (ib. .r) has a pit at its apex. 

 The prezygapophyses (fig. 12, z), of very small size, project from the outer and fore 

 border of the neural arch, with their articular surface looking outward and slightly 

 upward; a ridge is continued from their back part to the base of the postzygapo- 

 physes: the surface (fig. 13, z') in these, A^ lines in long diameter, is three times the 

 size of the anterior one ; it is concave transversely, and looks downward and a little out- 

 ward. The anapophyses (ib. fig. 12, a) are large tubercles rising above the articular 

 surfaces. The base of the nemal spine, 9 lines in length (ib. ns), is coextensive with 

 the neural arch ; the spine rises posteriorly to a height of 6 lines, with a thickness of 2 

 lines, having a convex upper margin (PI. XV.). 



The relative size and position of the cervical vertebrse, as coadjusted in the position 

 and degree of flexure of the neck represented in Sir Hans Sloane's life-size paintmg of 

 the Dodo, in the British Museum, are given in Plate XV. with the varying proportions 

 of the pleiu-apophyses and other processes. 



§ 3. Bibs. (Plates XV. & XVI.) 



The specimens of ribs include both vertebral and sternal portions ; that which appears 

 to be the second or thii-d on the right side (PI. XVI. figs. 7, 7 a) is 4 inches 4 lines 

 m length (following the outer ciu've), and expands to a breadth of 7 lines at its lower 

 part; the interval between the articular sm-faces of the head and tubercle is 6 lines. 

 The appendage (ib. a) has coalesced with the middle of the hind margin of the shaft. 

 The neck js compressed, with a thin upper margin ; the lower one is continued with 

 a curve upon a strong internal buttress-like ridge (ib. b), which runs to near the fore 

 part of the flattened body of the rib, where it meets the ridge continued from the 

 tubercle, about 2 inches down the rib: there is a shallow channel between these 

 ridges, contracting to their confluence. The inner surface of the rib is impressed by 

 a deeper and broader channel behind the buttress: the posterior border expands in 

 in the form of a triangular plate, with a base of about an inch in extent, due to the 

 complete confluence there of the epipleural process. The anterior border is thicker, 

 and is almost straight. Towards the sternal end the pleurapophysis contracts and thickens, 

 terminating in a rough syndesmotic elliptical surface, 3 lines by 2 (fig. T,f), for the at- 

 tachment of the haemapophysis or sternal rib. 



A vertebral rib (ib. fig. 2) which is entire, measures 9 inches in length (following the 



