MEM. M. C. Z., IX. No. 3. — ACALEPHS, POLYPS. 41 



being more pronounced below than above, carry tlie aperture obliquely upward (compare K^l). Some of 

 the mesenteries are clearly prolonged from the curved portion of the periphery across to the straight — or 

 chord — portion corresponding to the line of separation. The latter side subsecjucntly assumes the appear- 

 ance of a hilus. 



A view of the base eight days later (J'] shows it almost completely rounded, and in the region of the 

 former hilus the formation of two new chambers is confusedly indicated. It is to be seen upon sagittal 

 sections that in the region of tlie hilus some of the mesenteries are certainly formed by the development 

 of the distal portion of the central mesenteries of the opposite or curved side, others by the regular growth 

 of the mesenteries occupying tlic folded ends of the off-shoot, and still others by a new local origin ; also 

 that the infolded portions previously mentioned gradually come to form the pharynx. 



At length, after six days more (K', K"), the oH'-shoot is developed into a minute young actinia with 

 nearly central mouth and twelve tentacles. Upon the base are readily recognized six primary chambers 

 (1-6), — of which i are old and 2 are new, — 6 secondary, and 12 spurious chambers. The gonidial cham- 

 ber's correspond to 1 and 4. 



A (I'-Vf days later it had become quite regular, and showed traces of craspcdi {mesenterial filaments) on 

 the gonidial mesenteries. 



