THK ANATOMY OF HYLA CMRULEA WHITR. 



II.— THE SKULL. 



By C. D. Gillies, M.Sc, and Edna F. Peberdy, B.Sc. 

 (Biology Department, The L^niversitj^ of Queensland). 



With Two Text Figures. 



{Bead before the Royal Society of Queensland^ 29th October 



1917). 



The skull is semicircular in outline, but as the ratio 

 of length to breadth is about 4 : 5 it is not so long as wide. 

 By careful treatment with sodium hydroxide solution the 

 premaxillse, maxillae, quadrato-jugals, nasals, vomers, 

 palatines, pter\'goids, squamosals, sphenethmoid and 

 parasphenoid maj' be disarticulated. Usually, however,, 

 the latter is difficult to remove, as it is more or less fused 

 to the occipito-otic region. The posterior portions of the 

 fronto-parietals are more firmly united with this region sa 

 disarticulation only takes place anteriorly with the sphenet- 

 moicl. 



(a) The Cranium. 



There is a prominent occipito-otic region {oc.ot) formed 

 b}- the fusion of the exoccipitals and pro-otics. The 

 chondrocranium is almost entirely replaced by the occipito- 

 otic region and the sphenethmoid (sph.eth.). Both the 

 glossopharyngeal and vagus penetrate the occipital region 

 by distinct foramina, the inner and larger of which being 

 that of the vagus, but posteriorly the two foramina become 

 confluent and give rise to a shallow fossa (fig. II, IX. X.) 

 situated on the outer side of the base of 'the related condyle . 

 Dorsal to the latter is a prominence of the occipito-otic 



