Miscellaneous. 459 



On comparing the parietal segment of the skull in the Teleosaur 

 and existing Crocodiles, the first difference to be noted is the greater 

 proportion of the external surface of that region of the skull which 

 is contributed in the Teleosaur by the basi- and ali-sphenoids : they 

 maintain more of their normal shape and proportions in the ancient 

 Crocodiles. In the modern ones the lower surface of the basisphe- 

 noid is little more than the edge of the wedge, just expanding enough 

 at its middle to contribute part of the eustachian outlet, with a 

 scanty portion of a free smooth surface, on each side, in the Gavial. 

 The alisphenoid in modern Crocodiles has the whole of its outer sur- 

 face broken up into irregular parts of the auditory cavity : it offers 

 no surface of attachment for the crotaphyte muscles. The sides of 

 the parietal descend much lower, to compensate for the restricted 

 outer expansion of the alisphenoid. The parietal is much shorter, 

 has a broad and flat sculptured quadrate surface between the tem- 

 poral fossae ; and the posterior margin does not overhang, but is a 

 little in advance of the superoccipital. 



The Gavial differs from the Crocodile in the greater outward pro- 

 duction of the posterior angles of the parietal, and in that respect 

 more resembles the Teleosaur. The parietal of the Teleosaur retains 

 more of the normal type : it is not, however, perforated as in Ena- 

 liosaurs and Lacertians. 



The presphenoid is represented by a pointed styliform compressed 

 production of the basisphenoid. 



The orbitosphenoid is of great fore-and-aft extent, deeply exca- 

 vated internally where it forms the side of the widest part of the 

 cerebral cavity, protecting, as in the Crocodile, the cerebral hemi- 

 spheres : externally the bone is convex vertically, concave length- 

 wise ; expanding anteriorly to form the back part of the orbit, uniting 

 with the parietal and frontal above, with the alisphenoid behind, and 

 with the basi-pre-sphenoid below. 



Traces of the frontal suture remain longer in the Teleosaur than 

 in the Crocodile, especially on the inner surface ; but the frontal is 

 a single bone long ere the Teleosaur is adult. It is of an elongate 

 subhexagonal form, the long lateral borders emarginate for the 

 orbits : the posterior border is notched at the middle, and is im- 

 {)ressed on each side of the upper surface by the fore part of the 

 temporal fossae : the broad interorbital tract is flat : the inferior 

 cerebral surface is long and narrow, bounded laterally by moderately 

 curved sharp vertical ridges, convex towards each other, concave 

 towards the orbits. 



In modern Crocodilia the vertical diameter of the orbitosphenoids 

 exceeds the longitudinal one : the frontal is not impressed by the 

 temporal fossae, and the interorbital space is concave through the 

 elevation of the upper borders of the orbits. 



The postfrontals have their sculptured outer surface almost ver- 

 tical in the Teleosaurus : it is horizontal in modern Crocodilia : in 

 the Teleosaur it is produced much further back, and forms a larger 

 proportion of the upper zygoma : it is also continued upon the de- 

 scending process which joins the malar, whilst in modern Crocodilia 



