122 



ODOXTORXITIIES. 



The olfactory lobes of Ichthyomis (figure 29, ol) were large and 

 prominent. They were separated in front by the inter-orbital septum, and 

 their crura made then- exit, apparently, through separate foramina. 



The cerebral hemispheres were of moderate size, and proportionally 

 less elongate than in Hesjjerornis. Their form and proportions, in Ichthy- 

 omis victor, are well shown in figure 29, c, which represents a cast taken 

 directly from a cranium with this portion well preserved. 



The optic lobes (figure 29, oj>) are very large, and the brain at this 

 part was nearly as wide as across the hemispheres. The cerebellum (cb) 

 was large, and elongate. 



The general form and dimensions only of the posterior part of the 

 brain of Ichthyomis are shown in figure 29, and hence are indicated by a 

 uniform shading. The outline given was obtained from a comparison 

 and measurements of two different specimens. 



Figure 29. — Outline of the skull and brain-cavity of Ichthyomis victor, Alarsh ; seen from above ; five-sixths 



natural size. 

 Figure 30. — Outline of the skull and brain-cavity of Sterna cantiaca, Gmelin; same view; natural size. 



ol. olfactory lobes ; c. cerebral hemispheres ; op. optic lobes ; cb. cerebellum. 



