DEVELOPMENT OF THE STAEFISH SOLASTEE ENDECA. 63 



PLATE III. (conL). 



Fig. 33. Frontal section of a S. papposa larva at stage similar to that shown in fig. 31- 

 The section passes to the dorsal side of the mid-frontal plane. It will be 

 observed: — (]) That the enteron still opens widely in front into the 

 anterior ccelom, the opening looking leftward ; (2) there is a very definite 

 pouching to the right of the posterior part of the enteron ; (3) the right 

 gastric fold contributes a good deal more than the left one to the area of 

 the enteron. Although it does not appear in this section, the blastopore 

 is still widely open, and the enteron still communicates with the posterior 

 coelom. (x 45.) 



Fig. 34. From sagittal series of larva at stage when the flexion and torsion of the pre- 

 oral lobe (p. 16) is in early progress, the section being to the left of the 

 middle line of the body, but practically mesial at the anterior end of the 

 frontal lobe. A good part of the length of the muscular band concerned 

 in the movements mentioned above come into the section. Pouch IV of 

 the hydroccele, the sucker, and the anterior larval arm are also seen. 

 (X 45.) 



Fig. 35. Section of egg-tube of an adult S. endeca, after long fixation in an osmic 

 acid mixture (Lindsay Johnston fluid). Ova in diflferent stages of growth 

 are illustrated with special reference to the accumulation of the yolk- 

 granules, which have undergone an intensely black coloration (p. 6). 

 Similar granules along with larger ones are seen in the layer of follicle-cells 

 round each ovum, as also in the spaces between the ova within the lumen 

 of the egg-tube. (X 90.) 



