238 PROFESSOR OWEN ON THE GENIJS DINORNIS. 



Of the axis vertebra, the following are the relative dimensions in Binornis parvus 



and D. maximus : — 



miUim. millim. 



Length 23 60 



Breadth 25 58 



Height 28 60 



The base of the centrum in Binornis parvus develops a feeble submesial longitudinal 

 ridge ; its smooth fore ' preaxial ' articular surface is adapted to the hind surface of 

 the atlas, but is transversely concave in the same slight degree in which that is 

 convex; it is not divided by a non-articular depression, as in Binornis maximus, 

 from the convex articular undersurface of the odontoid (c). The ridge on the fore 

 part of the haemal surface of the hypapophysis is not developed in B. maximus, 

 but is so in Strtdliio, and in a greater relative degree in B. parv^is. The fore surface 

 of the 'centrum proper' is confluent with the hypapophysis and with the centrum 

 of the atlas (odontoid process). The hind ' postaxial ' articular surface of the 

 second vertebra is convex transversely, concave vertically, the transverse convexity 

 becoming feebly concave at the lateral borders, making a minor approach to the 

 angular outline than in B. maximus. The hypapophysial process of the proper 

 centrum of the axis resembles in shape and proportions that in B. maximus. 



The neural canal (figs. 8, 9, n) is two thirds the length of the entire vertebra, and its 

 width is one third of the breadth ; the anterior outlet is subcircular, 8 millim. in 

 diameter; the posterior outlet is transversely elliptical, 10 millim. across, and but 

 6 millim. vertically. In B. maximus the two diameters of this outlet are each 18 

 millim. The parapophysis (ib. fig. 9,^) has not the same relative lateral extension 

 as in B. maximus (loc. cit, fig. 7, p), the centrum of the axis in B. parvus being there 

 relatively narrower. The rudiment of the pleurapophysis developed from the middle 

 of the outer surface of the vertical bar completing the vertebrarterial canal in 

 B. maximus (ib. figs. 5, 6, ])l) is not present in B. j^arvus. From the diapophysial 

 plate completing that canal, the small prezygapophysis is developed with an articular 

 surface looking outward and slightly upward ; the postzygapophysis (fig. 9, z'} 

 differs chiefly in size from that of the atlas. The neural spine is a strong and seemingly 

 simple process ; but its summit is wanting. 



The succeeding cervicals retain the generic characters of those in Binornis. But 

 the main diflPerence, as already remarked, is shown by their superior number, at least 

 in the complete skeleton of the present diminutive Moa. 



The third cervical has a large compressed hypapophysis ; but this abruptly subsides 

 to a low ridge in the fourth, and disappears in the succeeding cervical, to give place, as 

 it were, to the parial inferior processes which begin to be developed from the parapo- 

 physes of the fifth cervical. 



In the third and several following cervicals the neural spine is represented by a pair 



