136 



VISION 



Figure 11 Dorsal and midsagittal views of the cerebellum of (A) Squalus acanthias, (B) 

 Rhinobatos productus, and (C) Myliobatis freminuvillii. Rostral is to the left of the figure. 

 A, anterior lobe; M, middle lobe; P, posterior lobe. Extent of cerebellar ventricle (indi- 

 cated in black) in Myliobatis is greatly distorted due to reconstruction; actual ventricular 

 extent is comparable to other sagittal sections. 



within which a set of brain: body data exist for a taxon. Such a region is 

 represented by a principal axis defined for a set of points distributed 

 rectangularly in the area in which they lie. This area and its principal axis can 

 be enclosed by a minimum convex polygon, which then maps the area of the 

 sample set. 



Figure 18 illustrates Jerison's (1970) evaluation of the avian, osteichthyan, 

 and mammalian data collected by Crile and Quiring (1940). The stippled 

 polygon encloses the elasmobranch brain: body data reported by Ebbesson 

 and Northcutt (1976) and Northcutt (19776). All elasmobranch data are 

 listed in Table 2, and a detailed plot is presented in Figure 19. 



