HISTORICAL SKETCH. XXI 



1904. The Structure of Bothriolepis, with Exhibition of Specimens of Devonian Fishes 

 of Canada. Read before the Am. Soc. of Zoologists, Phila. 



1907. On the Origin of Vertebrates. I. The Conditions Controlling the External 

 Morphology of Primitive Vertebrates. Lantern Slides. Read before Section 

 VII, General Zool, VII. International Zool. Congress, Boston, August. 



1907. On the Origin of Vertebrates. II. The Interpretation of the Structure of Echino- 

 derms, Ascidians, Balanoglossus, and Cephalodiscus. Lantern Slides. Ibid. 



1907. International Congress, Boston, Mercator Projections of Vertebrate and Arachnid. 

 Embryos. 



Exhibits. A. Collection of Bothriolepis from the Devonian rocks of Nev? 

 Brunswick. 



B. Fifty Models Illustrating the Structure and Embryology of Primitive Verte- 

 brates and Related Forms. Reviewed in Amer. Nat., Vol. XLI, No. 490. 



