<a 
Figs. 44-48. — Evolution of caudal fin. 44. Embryonic caudal of Amia. 45. Hetero- 
_cercal caudal of shark, Cestracion. 46. Heterocercal caudal of Cladoselache. 47. Diphy- 
_ cercal caudal of Polypterus. (After L. AGASSIZ.) 48. Homocercal caudal of Teleost. 
- (After RYDER.) 
_ 2. Dermal fin supports. Z. Lateral line. 44. Spinal cord. A7C. Membranous caudal. 
_ 4%. Notochord. N+, and R+N. Neural spines, including probably radial and basal 
elements. #. Radials. R+-H. Hzemal arch and spine; includes as well, probably, radial 
. aad basal elements. 
i. 37 
