1905.] 



AXATOMY OF THE FRILLED LIZARD. 



21 



not in reality belong to the arcli to which it is attached, but is a 

 persisting fragment of the second postoral arch, we should be 

 able to bring the Lacertilia into line with the Chelonia, where 

 the true hyoid arch is small and is followed by two better developed 

 branchial arches. At present, however, I can only make the 

 suggestion, after recording the facts. 



Text-fig. 10. 



Hyoid of Physignathus. a as in text-fig. 9. 



Vertebral Column and Ribs. — I find in Chlamydosaurus that 

 there are 23 presacral vertebrae and 49 caudals ; of the latter I am 

 inclined to think that none are missing. Of cervical vertebroi, 

 that is vertebrae entirely without ribs, I found in two individuals 

 jive^ which is one or two more than the usual number. The last 

 intercentrum of the anterior vertebrae lies between Nos. 6 and 7. 

 The dorso-lumbar vertebrae all possess ribs, even the last of the 

 series, which in the Agamidse generally * does not bear free ribs. 



* Siebeiirock, " Das Slvelet der Agamidse," SB. k. Akad. Wiss. Wien, vol. civ. 



