DEVELOPMENT OF THE GASTRiEA, 



65 



animals, with the exception of the Protozoa. This highly 

 important fact justifies the inference in accordance with the 

 fundamental law of Biogeny, that the various ancestral 



Fig. 174. 



Fig. 119. 



Fig. 174. — (A) Gastmla of a Zooptyta (Gastrophysemd), Haeokel, 



Fig. 175. — {B) Gastrula of a Worm (Arrow- worm, Sagitta). After Kowa- 

 levskj'. 



Fig. 176. — (C) Gastrula of an Bchinoderm (Star-fish, Uraster). After 

 Alexander Agassiz. 



Fig. 177.— (D) Gastrula of an Arthropod (Primitive Crab, Nawplius). 



Fig. 178.— (£) Gastrula of a Mollusc (Pond-snail, Limncsus). After 

 Karl Kabl. 



Fig. 179.— (F) Gastrula of a Vertebrate (Lancelot, Amphioxus) After 

 Kowalevsky. 



