PLATANISTA. 467 



degree it has Elex^liantine characters, viz., height and moderate breadth, though one 

 cannot regard.it in any other light than that of a modified Cetacean form. 



Fiff. 16. 



Outlines of the casts of the cranial cavities of Orcella and Platanista, the latter the internal, and the former th 

 external, outline : drawn to one scale. 



Mould of cranial cavity. — The admeasurements of the mould of the cranial 

 cavity of the adult are as follows : — 



Inches. 



Greatest antero-posterior length (prominence of frontal lobe to postcerehellar pronainence) . 3'25 



Greatest breadth {viz., temporo-occipital region) 3*65 



Diameter at the middle of frontal region, in front of Sylvian depression .... 2'80 



Greatest height (fronto-parietal region) 3'00 



Extreme length of each cerebral hemisphere 3'10 



Cerebellum in antero-posterior diameter about 1"20 



Cerebellar extreme breadth about • . 2'20 



Vertical height of cerebellum, including the pons Varolii 1*80 



The top view of this cast shows at a glance what is even in some degree apparent 

 in the shrunken brain, and which the second and third measurements above amply 

 substantiate, viz., the marked difference in width between the fore and after parts of 

 the cerebrum, that is to say that, while, as a whole, the brain of Tlatanista is broad 

 to its length, the great preponderance of breadth is at the occipito-temporal lobes ; 

 whereas the frontal width is in reality moderate. Erom above, this cast also shows 

 two nipple-like projections in the position of the olfactory lobes, but dependent rather 

 on ethmoidal depressions than on absolute olfactory nervous expansion. The con- 

 siderable exposure of the cerebellum is verified in this view of the cast ; and the 

 lofty hemispheres of the cerebrum, the deep valley of the longitudinal fissure and 

 especially the open angle of the posterior and inner cerebral angles are all 

 characteristic features. 



In the anterior face, the orbit o -frontal regions stand forward, whereas the 

 supraf rental areas retire. The lower latero-f rental eminences again are distinctly 

 impressed, compared with the occipito-temporal prominences ; these latter in this 

 foreshortened view standing out almost like wings to the former. 



The profile is exceedingly characteristic, for the exceeding loftiness of the 

 cerebrum, compared to its length, strikes one as something most unusual. The very 

 different sweep of the sharply rounded occipital border to the top of the brain, as 



