22 THE ELASMOBRANCH FISHES 



1907. OSBURN, E. C, New Evidence from Primitive Sharks on the Origin of the Limbs of 



Vertebrates. Science (n. s.), Vol. 25, pp. 729-730. 

 1907. OsBURN, R. C, Observations on the Origin of the Paired Limbs of Vertebrates. 



Amer. Jour. Anat., Vol. 7, pp. 171-194, pis. 1-5. 

 1907. OsBURN, R. C, The Origin of Vertebrate Limbs. Recent Evidence upon this Problem 



from Studies on Primitive Sharks. Ann. N. Y. Acad. Sci., Vol. 17, Pt. 2, pp. 415-436. 

 1906. Rennie, John, Accessory Fins in Raia batis. Anat. Anz., Bd. 28, pp. 428-431, 2 



text figs. 

 1877. Thacher (see p. 87). 

 1892. Woodward, A. S., The Evolution of Fins. Nat. Sci., Vol. 1, pp. 28-35, 8 text figs. 



