40 Travsactions. — Zoology. 



I have examined twenty atlas vertebras. In none is the 

 vertebral groove behind the lateral mass completely bridged 

 by bone on both sides ; but in three a complete foramen is 

 present on one side, while in six others an inij)erfect arch was 

 noted in this position. In one of the bones in which this 

 foramen occurs the rarer condition of a bony bridge passing 

 from the lateral mass to the upper surface of the transverse 

 process is also present. 



Fusion of the atlas with the occipital bone was seen once. 

 This occurs in a female skull, and the anchylosis is between 

 the lateral masses and anterior arch of the atlas and the cor- 

 responding parts of the occipital. 



The axis in one instance seems to have articulated with 

 the margin of the foramen magnum. In this bone a distinct 

 flat eburnated surface occurs on the anterior surface of the 

 tip of the odontoid process. 



Dorsal Vertebra. 



The average dorso-vertebral index of the nine columns 

 measured is 106-2, showing the posterior depth of the bodies 

 to be greater than the anterior. This difference is most 

 marked and most constant in the lower half of the dorsal 

 region. The indices vary from 104-3 to 111-6. 



The transverse measurements of the bodies show that the 

 smallest vertebra, as in the European column, is either the 

 fourth or the fifth. I should mention that in taking this 

 measurement I have omitted the projection of the costal 

 articular surfaces. The antero-posterior diameters show a 

 steady increase from the first to the last vertebra. In several 

 columns in the lower part of the region the maximum 

 diameter is oblique, passing anteriorly somewhat to the 

 right. 



The costo-central articulations do not differ much from the 

 ordinary European type. In one column from Hawke's Bay 

 the last rib to articulate with two vertebrae is the eighth. 

 The eighth vertebra has therefore one demi-facet above on 

 each side of its body, and none below. The ninth has a 

 single facet, as have also the tenth and eleventh. The usual 

 costal facet on the twelfth vertebra is not present, but instead 

 there is a small articular surface on the outer side of its trans- 

 verse process. This vertebra therefore closely resembled a 

 lumbar when its costal process was in position. In another 

 column a similar condition of the twelfth vertebra was noticed, 

 the rib-surface being very small, and much further back than 

 usual. In one column the tenth rib articulates with the 

 ninth dorsal vertebra, as is not uncommonly seen in Euro- 

 peans. In three cases there is no articulation on either side 

 between the transverse process of the tenth dorsal vertebra 



