DR. E. B. WILSON ON THE DEVELOPMENT OF RENILLA. 
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jp.s. 
Peduncular septum. 
s. 
Septa. 
si 
Supporting lamella. 
sp. 
Spicule or spicule cell. 
St. 
Stomodseum. 
t. 
Tentacle. 
V. 
Ventral chamber or ventral side. 
v.s. 
Ventral septa. 
v.cx. 
Ventral (ventro-lateral) calyx-teeth. 
v.f. 
Ventral mesenterial filaments. 
v.l.s. 
Ventro-lateral septa. 
v.l.f. 
Ventro-lateral mesenterial filaments. 
v.l.ch. 
Ventro-lateral chamber. 
y- 
Yolk. 
z. 
Inhalent zooids. 
PLATE 52. 
Figs. 1 to 14. Segmentation of an egg which divides at first into eight spheres. Time 
as follows:—Fig. 1, 8.50 a.m. ; 2, one minute; 3, two m.; 4, seven m.; 
5, ten m.; 6, twenty-five m.; 7, thirty-four m.; 8, fifty-five m.; 9, sixty- 
three m.; 10, sixty-eight m.; 11, seventy-five m.; 12, ninety m.; 13, ninety- 
eight m.; 14, one hundred and fifteen m. X 85. 
Figs. 15 to 18. Continuation of segmentation, from another specimen. Time as 
follows:—Fig. 15, 10 a.m.; 16, ten m.; 17, twenty-seven m.; 18, thirty- 
two m. X 85. 
Figs. 19 to 24. Unusual mode of segmentation. Time as follows:—Fig. 19, 
7.55 a.m.; 20, two m.; 21, ten m.; 22, twenty m.; 23, twenty-three m. ; 
24, forty m. X 65. 
Figs. 25 to 27. Division of an egg into two spheres. X 65. 
Figs. 28, 29. Egg divided into four spheres. X 65. 
PLATE 53. 
Figs. 30 to 37. Segmentation of an egg which divided at once into sixteen spheres. 
Time not recorded. X 65. 
Figs. 38 to 41. Unequal segmentation beginning with sixteen spheres. Time as 
follows:—Fig. 38, 9.7 a.m.; 39, same in different position; 40, thirty- 
three m.; 41, thirty-six m. X65. 
Figs. 42 to 44. Another specimen illustrating unequal segmentation beginning with 
