92 PALÈOZOOI.OGIE ET PALÉOPHYTOLOGIE 



être poussée plus à fond ; on remarquera parLiculièremeni la reconstitution 

 des pattes avec les éléments épars sur cette lielle plaque. A^. Oldenburgi paraît 

 caractérisé par le galbe plus étroitement allongé du crâne, avec les dents 

 en partie conservées de part et d'autre. Une figure est donnée à l'appui de la 

 présence d'un fragment de crâne de A'^. marchicus dans ce gisement. Â^. erassus 

 se distingue par la forme massive du crâne, cependant l'épipLérigoid ressemble 

 à celui de A'^. procerus. 



Le chapitre final contient la comparaison collective de ces espèces avec 

 Cymalosaurus qui semble plutôt localisé dans le Muschelkalk inférieur, 

 puis des figures précisant l'emplacement des nasales dans les deux groupes : 

 le passage au groupe Eurysaurus reste plus douteux. 



Sollas, W. J. On the Structure of Lysorophus, as exposed by serial 

 SECTIONS. Phil. Trans. Roy. Soc, ser. B., vol. 209, pp. 481-527. 1 pi. 

 Londres, 1919. 



The skull and anterior région of the body of two spécimens were investi- 

 gated, serial sections being obtained in one case at intervais of 0.1 mm. 

 and in the other of 0.2 mm. Thèse revealed the structure of the parts in 

 détail with a completeness that leaves nothing to be desired. 



The articulation of the skull with the vertébral column is particularly 

 interesting. The vertèbres are deeply amphicœlous with the exception of the 

 first which is opisthocœlous. The anterior face of this vertebra is swollen 

 into a rather cylindrical convexity which plays against the shghtly concave 

 posterior surface of the basi-occipital. In addition however it articulâtes 

 by the antero-lateral corners of its upper face with the « heel » of the exocci- 

 pitals, and thus présents an almost indiffèrent stage which might lead either 

 to a reptilian or an amphibian articulation. The articulation of the .skull 

 with the vertébral column is however not confined to the centrum of the 

 first vertebra for the piers of the neural arch are in close contact with the 

 «stem» of the exoccipitals,and the pro-atlasis closely apposedto the exocci- 

 pitals of the supraoccipital. Hère we are reminded of an arrangement which 

 occurs in some bony fishes. 



The exoccipitals are perforated by a foramen for the tweifth nevve : 

 between the exoccipital and opisthotic is the jugular foramen which no 

 doubt gave passage for the tenth nerve ; between the pro-otic and the slapes 

 is the foramen pro-oticum for the fifth and seventh nerves. 



Rising from the large and characteristically Urodele parasphenoid just above 

 the foramena for the palatine branch of the facial nerve are two stout pillars, 

 one on each side, which articulate with the parietals, thèse are the columella 

 cranic ; further forward are the anterior wales of the skull, analogous if 

 not homologous with the orbito-sphenoids. 



The prefrontal near its anterior end gives oft a process on its side which 

 curves outwards and downward to meet a corresponding process which 

 arisis from the maxilla sinthis way acanal, incomplète on the inner side, 

 is formed which may hâve lodged a tentacular organ. 



The bone which has hitherto been taken for the quadrate is the squamosal 

 and the true quadrate hes wedged in between the extremity of the squamosal 

 and the pterygoid. 



