812 
DR. B. B. WILSON ON THE DEVELOPMENT OF RENILLA. 
Fig. 115. The same, eleven days. At a is the posterior thickened region which 
secretes the axis. X 50. 
Fig. 116. The same individual, twelve days. X 50. 
Fig. 11 6 a . Part of wall of body more highly magnified to show spicules in ectoderm. 
Fig. 117. The same, thirteen days. Mesenterial filaments well developed. X 50. 
Fig. 118. Section through Leptogorgia embryo of six hours. X 160. 
Fig. 120. Section through Renilla embryo of about four hours. X290. 
PLATE 57. 
Fig. 119. Section through Renilla embryo of four and three-quarter hours. 
Fig. 121. Section through an embryo of eight and a-half hours. X290. 
Fig. 122. Portion of a section of same stage more highly magnified. X 880. 
Fig. 123. Same as last. X 880. 
Fig. 124. Yolk cells from last with deutoplasm spherules. X880. 
Fig. 125. Longitudinal section through embryo of twenty-two and a-half hours. X 195. 
PLATE 58. 
Fig. 126. Portion of same more highly magnified. X 350. 
Fig. 127. Part of a section through a twenty-five-hours’ embryo. X350. 
Fig. 128. Longitudinal section through a twenty-nine-hours’ embryo. X 165. 
Fig. 129. Part of the same more highly magnified. X 350. 
Fig. 130. Part of section through a fifty-two-hours’ larva. X 350. 
Fig. 131. Part of section of a twenty-eight-hours’ embryo to show proliferation of 
ectoderm. X350. 
Fig. 132. Part of section through an embryo further advanced than the last to show 
formation of supporting lamella; a represents a single ectoderm cell with 
swollen base, b; bb are the rounded bodies which have separated from the 
ectoderm cells; c is one of the rounded cells from the deeper parts of the 
ectoderm, x 350. 
Fig. 133. Part of longitudinal section through a twenty-six-hours’ embryo to show 
formation of supporting lamella. 
Fig. 134. Longitudinal section through a forty-hours’ larva to show formation of 
stomodseum. X 230. 
PLATE 59. 
Fig. 135. Longitudinal section through a forty-eight-hours’ larva. X230. 
Fig. 136. Vertical longitudinal section through a fifty-two-hours’ larva. X 165. 
