248 WILSON. 
DESCRIPTION OF PLATE V. 
Fics. 30, 31, 32, 33. Series of trans. sec., numbered from above down, from a 
larva with two pretty long (half the length of larva) and one very short filament. 
The first and third filaments have been formed from a common lobe, and the third 
mesentery (4) has been formed at the same time and in the same way as the first (a), 
1D Ae 
Fic. 34. Trans. sec., below cesophagus, of attached larva with eight mesenteries. 
185 
Fic. 35. Trans. sec. through upper part of one of the primary filaments of an 
attached larva. The large clear cells are nettle cells. F, 4. 
Fic. 36. Trans. sec., through cesophagus, of attached larva with eight mesenteries. 
The second pair of mesenteries is not quite complete, and consequently at this level 
(just above the lip) the reflected ectoderm is found all round the cesophagus. B, 4. 
Fic. 37. Long. sec. through attached larva; on the right through one of second 
pair of mesenteries, on the left through an intermesenteric chamber. C, 2. 
Fic. 38. Long. sec. through attached larva in which the basal plate has appeared; 
on the left through one of third pair of mesenteries with its filament, on the right 
through an intermesenteric chamber. The line m, m indicates the outline of the 
polyp when expanded. C, 2. 
Fic. 39. Trans. sec., through cesophagus, of attached larva with twelve mesen- 
teries. B, 4. 
Fic. 40. A more highly magnified view of one of the septa of Fig. 41 (that lying 
in the near “directive” chamber), sectioned at the level of its opening. ¢.d. is the 
calycoblast layer. 
