a 
a 125: 
g. 
. 128. 
5 IPAS). 
. 130. 
5 Maule 
Fig. 
Fig. 
ig. 115, 
Pee: 
5 Laleyes 
Ba Ia ee 
as: 
2 120. 
5 ile). 
5 LbPaiL. 
5 ay, 
. 123. 
124. 
sel 26: 
127. 
. 132. 
133. 
134. 
oo: 
7, 136. 
DR. E. B. WILSON ON THE DEVELOPMENT OF RENILLA. 
The same, eleven days. At @ is the posterior thickened region which 
secretes the axis. X50. 
The same individual, twelve days. x 50. 
Part of wall of body more highly magnified to show spicules in ectoderm. 
The same, thirteen days. Mesenterial filaments well developed. x 50. 
Section through Leptogorgia embryo of six hours. X 160. 
Section through Renzla embryo of about four hours. x 290. 
PLATE 57. 
Section through Renilla embryo of four and three-quarter hours. 
Section through an embryo of eight and a-half hours. X 290. 
Portion of a section of same stage more highly magnified. x 880. 
Same as last. »X 880. 
Yolk cells from last with deutoplasm spherules. X 880. 
Longitudinal section through embryo of twenty-two and a-half hours. x 195. 
PLATE 58. 
Portion of same more highly magnified. x 350. 
Part of a section through a twenty-five-hours’ embryo. 350. 
Longitudinal section through a twenty-nine-hours’ embryo. X 165. 
Part of the same more highly magnified. 350. 
Part of section through a fifty-two-hours’ larva. x 350. 
Part of section of a twenty-eight-hours’ embryo to show proliferation of 
ectoderm. X350. 
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; ¢ is one of the rounded cells from the deeper parts of the 
ectoderm. x 350. 
Part of longitudinal section through a twenty-six-hours’ embryo to show 
formation of supporting lamella. 
Longitudinal section through a forty-hours’ larva to show formation of 
stomodeum. X 230. 
PLATE 39, 
Longitudinal section through a forty-eight-hours’ larva. 230. 
Vertical longitudinal section through a fifty-two-hours’ larva. X 165. 
