PROFESSOR OWEN ON THE GENUS DINORNIS. 261 



The following are comparative admeasurements of this vertebra, and a corresponding 



one of a full-grown Ostrich : — Dinomis. Simihio. 



In. Lin. In. Lin. 



Length 19 20 



Depth of anterior articular surface 10 7^ 



Breadth, including costal articulations 16 2 



From the lower margin of posterior articular surface to 



the upper one of posterior oblique process .... 2 1 18 



The spinous process of this vertebra is strong and square-shaped', and shows, like 

 the preceding dorsal, that there was no blending together of the spines, nor any union 

 by continuous splint-like ossifications, as in many birds, and especially in those that 

 fly. The dorsal region in the skeleton of the Dinornis, by the intervals separating the 

 spinous processes, must have resembled that in the large existing Struthionidte, and 

 have differed from the same part in the Apteryx, in which the dorsal spines are con- 

 tiguous though not confluent ; but the Dinornis surpassed all known birds in the thick- 

 ness and squareness of its upright spinous processes. Of the length of these processes 

 none of the five vertebrse afford an exact idea, all being more or less fractured. 



The spinal canal is proportionally more contracted than in the Ostrich, or even in 

 the Apteryx, where it is rather smaller than usual. This character in the Dinornis indi- 

 cates, of course, a more slender spinal chord, in which respect it betrays a closer ap- 

 proach to the Reptilia. We may associate, with such a condition of the spinal marrow, 

 less delicate perception, and less energetic muscular action ; and the vertebrae thus 

 confirm the induction from the texture of the femur, that the Dinornis was a more 

 sluggish or less active bird than the Ostrich. 



CONCLUSION. 



Physiological indications of the nature and proportions of the Anterior or Pectoral 



Members. 



Had the Dinornis wings ? To this question I was led to give a negative reply after 

 the examination of the first fragment of that bird's bone which came into my hands'. 

 It has appeared strange and almost incredible to some, that the cancellous texture of 

 the shaft of a thigh-bone should give, to speak mathematically, the presence or absence 

 of wings. But if the negative had been premature and unfounded, a guess rather than 

 a demonstration, its fallacy might have been exposed by the very next bone of a Dinor- 

 nis transmitted from New Zealand. A bird of flight has as many wings as legs ; it has 

 two humeri as well as two femora, two radii as well as two tibiae, two ulnae as well as 



' PI. XVIII a. fig. 7 



' Absence of the organs of flight is the essential character of a Struthious bird, more especially of one 

 " heavier than the Ostrich." 



2 m2 



