82 
ANNIE MATTHEWS. 
edge of their respective mesenteries, and the dorsal not quite- 
so far (Text-fig. 48). The first signs of each ventral filament 
Text-figs. 48-51. 
Fig. 48. Vertical section of polyp on thirteenth day of fixation, 
showing relative length of dorsal and ventral mesenteric 
filaments. Fig. 49. Transverse section of young dorsal 
mesenteric filament. Fig. 50. Longitudinal and radial section 
of very young ventral mesenteric filament, showing its relation 
to the thickened edge of the mesentery. Fig. 51. Transverse 
section of young ventral mesenteric filament. 
are found on the fourth day of sedentary life, shortly before 
the mouth is open. Immediately below the base of the 
