TllK ANNALS 



AND 



MAGAZINE OF NATL'ltAL HISTUKY. 



[SIXTH SERIES.] 

 No. 76. APRIL 1894. 



XX XI IT. — A Contribution to the Osteology of the Head of 

 Ilattoiiii*. By FiUEDKiCH Siebenrock, Assistant in the 

 Imperial and Royal Natural History Museum in Vienna. 



[Plate XIV.] 



The present memoir contains a precise description of the 

 interorbital septum, the anterior cartihigino-raembranous 

 cranial wall, and of the paroccipital, which is present in 

 Ilatteria alone among Saurians. 



In addition to this there follows a detailed account of the 

 several cranial bones, especially with reference to the bony 

 auditory structures contained witliin them. These are distin- 

 guished by the presence of the fossa cochlearis of the basi- 

 occipital, the junction of the orificium ampullae canalis semi- 

 circularis frontalis and the orificium canalis semicircularis 

 horizontalis in the posterior ampullary chamber of tlie 

 paroccipital, the absence of the foraneu nervi acustici, ramus 

 cochlearis, the absence of the foramen canalis Vidiani anterius 

 in the fossa hypophyseos, and by the remarkable structure of 

 the superior margins of the paroccipital and of the oto- 

 sphenoid. 



Finally, it will be shown that the parietal is paired even 



* Translated from the ' Sitzungsberichten der kaiserl. Akademie der 

 AVissenschaftea in Wien, JMathem.-naturw. Classe,' Bd. cii. Abth. i., 

 June 1893, pp. 250-268: from a separate impression, communicated by 

 the Author. 



Ann. & Mag. N. Hist. Ser. 6. Vol. xiii. 20 



