Anatomy of Acanthidositta chloris. 



: 



proc. sqvamosi ; as in the foregoing types, the tympanic wing 

 rises above the periphery of the tympanum. 



But in ("includes there is a low ridge running from the 

 processus sguamosi to the free projecting upper end of the 

 tympanic wing, and in Homorus the ridge becomes a broad 

 outstanding ledge forming, by its junction with the tympanic 

 wing, a pent-house over the head of the quadrate. In 

 Pseudocolaptes there is a similar ridge running from the 

 processus articularis sguamosi, which runs up to join the tym- 

 panic wing and so forms a shallow overhanging pent-house 

 above the tympanic cavity. There is no trace of this last in 

 Acanthidositta. 



The Vertebral Column. 



In so far as the prcsynsacral vertebrae of Acanthidositta 

 arc concerned, there is little that need be said. All are 



Text-fier. II. 



Ventral aspect of synsacrum, to shew the deep pittings. 



free. The last five cervical and the first two thoracic bear 

 well-marked hypapophyses, and this is true also of the 

 Synallaxine forms already referred to. 



The synsacral vertebras of Acanthidositta are remarkable 

 for a series of deep pits which occur in pairs separated by a 

 median bony ridge along nearly the whole ventral aspect of 

 this fused mass (see text-fig. 41). Only the last four caudals 

 lack these pits, and this because the centra are laterally 



