250 WILSON. 
DESCRIPTION OF PLATE VI. 
Fic. 41. Trans. sec. through cesophagus of young Manicina, iin. diam. D.JZ, 
the directive mesenteries. X, 60. 
Fic. 42. Section of same specimen, below cesophagus. Skeleton is bare at a and 
a’. The tip of the columella lies in the ccelenteron. X, 68. 
Fics. 43, 44, 45. Series of trans. sec., numbered from below upwards, through 
the oval cone of a larva like Fig. 38. Fig. 43 is through the line x, y in Fig. 38. 
Only the first two pairs of mesenteries extend into the uppermost part of the ccelen- 
teron. The overlapping of the reflected ectoderm and endoderm is well shown. D, 4. 
Fic. 46. Part of a trans. sec. of adult single polyp, through line a in Fig. 50. The 
ectoderm of the peristome is marked oe.ec.; that of the lateral body wall, ec. X, 30. 
Fic. 47. Trans. sec. of filament and mesentery of a larval Cerianthus. Level of 
section is just below the cesophagus. m is the commencing ciliated band (flimmer- 
streif). F, 2. 
Fic. 48. Section of same filament lower down. The violent contraction has 
caused the halves of the mesentery to spring apart, leaving the coagulated supporting 
lamella partially free. F, 2. 
Fic. 49. Trans. sec., through cesophagus, of a larval Certianthus. D.M., the 
(larval) directive mesenteries. The numbers 1, 2, 3, 4, mark the four youngest mes- 
enteries, in the order of their age, I being the youngest. X, 60. 
