252 WILSON. 
DESCRIPTION OF PLATE VII. 
Fic. 50. Median long. sec. through an adult single polyp; on the right through a 
primary, on the left through a secondary mesentery. The line 3 marks the position 
of the free edge of a tertiary mesentery. The surface of attachment was irregular, 
but the corallum extended only a very short distance below the limit of the skeleton 
in the figure. X, 30. 
Fic. 51. One of the extra-thecal entoccelic chambers of Fig. 49 more highly mag- 
nified. Jes. is the peripheral portion of a mesentery. 
Fics. 52, 53, 54. ‘Trans. sec. of an adult primary filament. Fig. 52 is through the 
upper, 53 through the middle, and 54 through the lower portion. The large clear 
cells in Fig. 53 are nettle cells. D, 4. 
Fic. 55. A more highly magnified figure of the lower portion of the cesophagus, 
as shown in the left halfof Fig. 50. Oe.ec. is the lining epithelium of the cesophagus. 
Fic. 56. One-half of a median long. sec. of an adult single polyp. The section is 
through one of the primary septa. X, 30. 
