3 66 



TYPES OF LARVAE. 



Of the larval forms included in the above list a certain 

 ec 



en 



en\ 



e.g. 



FlG. 215. TWO FREE STAGES IN THE DEVELOPMENT OF SYCANDRA RAPHANUS. 



(After Schultze. ) 



A. Amphiblastula stage. 



B. Stage after the ciliated cells have commenced to be invaginated. 



c.s. segmentation cavity; ec. granular epiblast cells; en. ciliated hypoblast cells. 



number are probably without affinities outside the group to 

 which they belong. This is the case with the larvae of the 



FIG. 216. THREE LARVAL STAGES OF EUCOPE POLYSTYLA. (After Kowalevsky.) 



A. Blastosphere stage with hypoblast spheres becoming budded into the central 

 cavity. 



B. Planula stage with solid hypoblast. 



C. Planula stage with a gastric cavity. 



<?/. epiblast; hy. hypoblast; al. gastric cavity. 



