Davenport. — Cristatella. 



PLATE IX. 



Fig. 77. Sagittal section through a polypide, of which the atrial opening {of. atr.) 

 has already begun to form, x 390. 



" 78. Horizontal section through the circumoral part of the ring canal, can. crc, 

 showing its free communication with the coBnocoel (cceti.). Adult. 

 X 175. 



" 79. Vertical section through the roof of the colony (to the left) and the 

 kamptoderm (to the right), showing their connection b^' the inferior 

 parieto-vaginal muscles (mu. inf.) at an early stage of their develop- 

 ment. X 600. 



" 80. Horizontal section in position marked 80, Fig. 72, Plate VIII., showing 

 epistomic canal, can. e stm., and supra-ganglionic part of ring canal, 

 can. crc.'" X 390. 



" 81. Section cutting lophophore at base of tentacles. The arm of the right 

 side only is shown entire. Stage of Fig. 77. x 175. 



