STUDIES ON THE COMPARATIVE ANATOMY OF SPONGES. 39 



overlying epithelium (ep.), which latter is cut almost taugeutially owing to the 

 unevenness of the surface, p. ep. Projection of the surface epithelium 

 around a protruding spicule, which latter is not itself seen in the section. 

 Spicules blue. Zeiss, F, ocular 4. 



Fig. 35. — An amoeboid ovum (ov.) lying in the gelatinous ground. substance 

 of the mesoderm, near the epithelium {ep.) of an inhalant canal. Zeiss, F, 

 ocular 3. 



Fig. 36. — An ovum {ov.) hanging by a stalk from the epithelium {ep.) of an 

 inhalant canal. Zeiss, F, ocular 3. 



Fig. 37. — Another example of an ovum (ov.) hanging by a stalk from the 

 epithelium (ep.) of an inhalant canal. Zeiss, F, ocular 3. 



Fig. 38. — An embryo (approaching the pseudogastrula stage) lying within 

 the embryo-containing capsule in the mesoderm, between two flagellated 

 chambers of the mother sponge, col. Collared cells of mother sponge, sp. 

 Spicule of mother sponge, end. Prismatic cells (future endoderm) of the 

 embryo, mes. Incipient mesoderm of the embryo, ffr. Layer of large 

 granular cells of the embryo. Other lettering as before. 



