DR. E. B. WILSON ON THE DEVELOPMENT OF RENILLA. 
813 
Fig. 137. Longitudinal section through a seventy-five-hours’ larva. (Esophagus still 
closed. X140. 
Fig. 138. Similar section through a slightly later stage (100 hours). X 140. 
Fig. 139. A similar section of a sixty-two-hours’ embryo; the oesophagus has just 
broken through. X 140. 
Fig. 140. Longitudinal section of seventy-five-hours’ larva. Mouth fully formed, but 
“oesophageal plug” (pi.) still adhering to the edge of one of the septa. 
X 140, 
Fig. 141. Sixty-hours’ larva. Mouth breaking through bottom of stomodseum. X 140. 
Fig. 142. Transverse section through anterior part of forty-eight-hours’ larva. X315. 
PLATE 60. 
Fig. 143. Transverse section from same specimen further back at the level of lower 
end of oesophagus. X 315. 
Fig. 144. Transverse section through anterior part of a four-days’ larva. X 315. 
Fig. 145. From same larva at lower end of oesophagus. X 315. 
Fig. 146. Transverse section of four-Mays’ larva posterior to oesophagus. X 350. 
Fig. 147. Part of a transverse section through a forty-eight-hours’ larva showing a 
septum and general histology. X 880. 
Fig. 147 ffl . Portion of ectoderm from last. X 880. 
PLATE 61. 
Fig. 148. Section through lateral attachment of peduncular septum to body-wall. 
Forty-eight hours. X350. 
Fig. 149. Section through radial septum and part of body-wall. Forty-eight hours. 
X 350. 
Fig. 150. Longitudinal section through posterior part of body of a forty-hours’ larva to 
show formation of peduncular septum. X 135. 
Fig. 151. Transverse section through posterior part of a forty-eight-hours’ larva showing 
peduncular septum. X 315. 
Fig. 152. Transverse section through the free-edge of the peduncular septum. Forty- 
eight hours. X180. 
Fig. 153. Part of longitudinal section through peduncular septum, highly magnified, 
to show axial cells, X 350, 
Fig. 154. Transverse section in front of peduncular septum. Forty-eight hours. 
X 315. 
Fig. 155. Longitudinal section just above peduncular septum. X 220. 
Fig. 156. Transverse section through peduncular septum at its attachment to the 
body-wall. Forty-five hours. 
MDCCCLXXXIII. 5 M 
