Miscellaneous. 461 



exclusively by the pterygoid, but having its pointed anterior end 

 produced between the diverging hind ends of the palatines. 



The eustachian outlet, regarded by Professors Bronn and De Blain- 

 ville as the true posterior nostril, is shorter and wider than in the 

 Gavial : the posterior primary division of the eustachian canal pene- 

 trates the basioccipital and expands there into a subcircular sinus : 

 the anterior primary division perforates the substance of the basi- 

 sphenoid and ascends obliquely forwards a little way before bifurcating 

 to form the anterior canals leading to the right and left tympanic 

 cavities, which are extended by the production of its air-cells across 

 the basioccipital and basisphenoid, and upwards into the tympanic, 

 mastoid, alisphenoid, exoccipital, superoccipital, and parietal bones. 



The temporal fossae vary in shape in different species of Teleosau- 

 rus, being sub quadrate in Tel. latifrons and Tel. Cadoinensis, oblong 

 in Tel. Chapmanni and Tel. brevior ; but they are always relatively 

 larger and with the upper outlets closer together than in the Gavial. 

 In most old and large Teleosauri the parietal is reduced to an inter- 

 muscular crest between them ; as is the mastoid, between their back 

 part and the occipital fossa. In general the upper zygoma is on a 

 lower level than the parietal, not as in modern Crocodilia on the same 

 level. The orbits, of a full oval form, look more outwards than up- 

 wards ; their rim is sharp, and not raised above the level of the rest 

 of the skull. 



The true external nostril is single, as in other Crocodilia ; but is 

 terminal, as above mentioned. 



Rudiments of the divided nostrils, situated as in Ichthyo- and 

 Plesio-saurif a little in advance of the orbits, are present in most 

 Teleosauri. I conjecture that they were not used as nostrils, but are 

 a typical retention of a structure, indicative of the closer affinities of 

 the Teleosauri to the Nothosauri and Enaliosauri. 



The modifications of the cranium of the Teleosaur, compared with 

 the modern Gavial, all bespeak its better adaptation for swiftly 

 cleaving the liquid element. The upper jaw, not suddenly, but gra- 

 dually, expands into the orbital region, and is not marked off by any 

 outstanding plates of prefrontal, lacrymal, or malar. The cranium 

 behind the orbits, moreover, goes on expanding to the occipital plane, 

 instead of contracting, or retaining its sides parallel, as in the Gavial. 

 The sloping of the sides of the temporal region, where it is formed 

 by the broad upper zygoma, is another modification which would 

 favour the progress of the head in a movement tending to roll it from 

 side to side, as it was pushed through the water. The diminished 

 expanse of the premaxillary end of the muzzle in the same degree 

 decreases the resistance of this part during aquatic progress. All 

 these cranial modifications harmonize with the amphicoelian verte- 

 bral column, the very small fore limbs, and comparatively large hind 

 limbs in a crocodile organized for marine existence. 



The lower jaw presents the same complex structure as in modern 

 Crocodiles ; a large vacuity also intervenes between the subangular, 

 angular, and dentary elements. The ramus is of relatively greater 

 depth at this part in some Teleosauri, e. g. T. brevior, than in the 



