ELASMOBRANCH BRAIN ORGANIZATION 



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Figure 14 Dorsal and midsagittal views of the cerebellum of (A) Mustelus canis, (B) 

 Prionace glauca, and (C) Isnrus oxyrinchus. Rostral is to the left of the figure. A, anterior 

 lobe; M, middle lobe; P, posterior lobe. 



reported for vertebrates. Coefficients of allometry range from 0.63 to 0.65 

 for mammals, 0.56 to 0.60 for amphibians, and 0.65 for teleosts (Bauchot 

 et al. 1976). 



The present sample of taxa is too incomplete to suggest trends within the 

 elasmobranchs that may have increased brain size (Figure 19). However, 

 comparison of species of comparable body size, such as Squalus acanthias, 

 Mustelus canis, and Sphyrna tiburo, suggests that the squalomorph sharks 

 may be characterized by low brain :body ratios and that the evolution of 

 the galeomorph sharks is characterized by a twofold to sixfold increase in 

 brain size. Similarly, the batoids range throughout the polygon, but the 



