TYPES OF COLLENTERA A SEA- ANEMONE. 155 



of the gullet, and to the base, and all the mesenteries are 

 ingrowths of the body wall. The cavity of the anemone 

 is thus divided into a number (some multiple of six) of 

 radial chambers. These are in communication at the base, 

 so that food particles from the gullet may pass into any 

 of the chambers between the partitions. Moreover, each 

 partition is perforated, not far from the mouth, by a pore, 

 besides which there is 

 often another nearer 

 the body wall. The 

 tentacles are continu- 

 ous with the cavities 

 between the mesen- 

 teries, and thus all the 

 parts of the body are in 

 communication. The 

 mouth is usually a 

 longitudinal slit, and 

 its two corners are 

 often richly ciliated. 

 The gullet is marked 

 with longitudinal 

 grooves, two of which, 

 the "siphonoglyphes," 

 correspond to the cor- 

 ners of the mouth, and 

 are especially broad 

 and deep. Along these 

 two grooves, and by 

 these two corners, food 

 particles usually pass 

 in ; but in some, one 

 side is an incurrent, 

 the other an excurrent 

 channel. Occasionally 

 only one corner of the 

 mouth and side of the gullet is thus modified. The gullet 

 often extends far down into the cavity of the anemone. 

 It admits of a certain amount of extrusion. The mesenteries 

 bear (a] mesenteric filaments ; (1)) retractor muscles ; (c) 

 ridges of reproductive cells, almost always either ova or 



FIG. 72. Vertical section of a sea- 

 nnemone. After Andres. 



/., Tentacles ; 0., mouth ; aes., oesophagus ; c., c'., 

 apertures through a mesentery ; a., a.'., acontia; 

 ., genital organs on mesentery ; m.f., mesen- 

 teric filaments; ;//./., longitudinal muscles; 

 s., primary septum or mesentery ; .?'., second- 

 ary septum; s"., tertiary septum; ?'., basal 

 disc. 



