102 PROP. W. K. PARKEE ON THE STRUCTURE OF 



b. Endocranial modifications in the Chameleons skull : 



14. The huge high supraoccipital crest. 



15. The absence of the rudiment of a cochlea, and of the fenestra rotunda. 



16. A very small and simple alisphenoid, instead of the normal basketwork of car- 

 tilage and bone. 



17. The orbito-nasal septum agrees with many in having the membranous space 

 enclosed (as a fenestra), and not open (as a notch), as in Lacerta. 



18. There is no cranio-facial fenestra between the perpendicular ethmoid and the 

 septum nasi. 



19. The ali-ethmoidal cartilages are notched for the nasal glands ; and there is no 

 fenestra, right and left, in the ali-septal roof. 



20. There is no free or confluent labial cartilage running between the snout and the 

 upper surface of the vomer, as in Lacerta ; but the ali-nasal annulus is much more evi- 

 dently a confluent (valvular) labial, corresponding to the outer upper labial of the meta- 

 morphosed Frog and Toad. 



c. Modifications of visceral arches in the Chammleon : 



21. There is no epipterygoid — a part which exists in all other Lacertilia known to 

 me, is largest in Ilatteria, and is present in all known Chelouia. 



22. The pedicle of the quadrate is a very distinct process from the otic process ; it is 

 much broader than in the Chelonia, but, as in them, has the tip unossitied. 



23. The columella keeps within the quadrate, has not a bifurcated supra-stapedial 

 process, has no infrastapedial, and is not functional ; there is no cavum tympani. The 

 hyo-branchial apparatus is very unlike that of the typical Lizard. 



24. The hypohyals are quite distinct from the basal bar and from the ceratohyals ; 

 the latter are not dilated below; both hypo- and ceratohyals are (normally) unossified. 



25. The basi- or glossoliyal is as long as the skull, is highly ossified, and has a small 

 unossified segment at its fore end and a non-segmented basibranchial process behind. 



26. The ceratobranchials are well ossified; they have no upper or epibranchial 

 segment, as in Lacerta ; there are no hypobranchial processes, or thyro-hyals, behind and 

 within them proceeding from the basal bar, which is narrow and rounded at the end. 



Comparison of the Chameleon's Skull with that of the Amphibia and the Chelonia. 



The skull of the Chameleon, in difiiering so much from that of the other Lacertilia, 

 does not, at the same time, approximate to that of other types below, aside of, or above 

 its own family. 



The Chameleon's skull resembles that of those Anura which have a columella but 

 no " cavum tympani," and also agrees with them in having neither a cochlea nor a 

 fenestra rotunda. It agrees with the Chelonians in having a single vomer and no 

 septo-maxillaries, and in having a crested supraoccipital, and with the Ophidia and 

 Crocodilia in having no epipterygoid. 



