ANEMONES 



381 



There is no special sphincter muscle. 



The tentacles possess a thick ectoderm which is crowded with 

 nematocysts and granular gland cells ; goblet cells also occur. Near 

 the base of the ectoderm is a layer of 

 nervous fibrillar substance. Between this 

 and the inconspicuous mesogloea are the 

 longitudinal muscles. The endoderm bears 

 about the same relation to the ectoderm as it 

 does in the capitulum. 



The oesophagus is readily eversible. The 

 specimen represented in Plate xxiv, fig. i, 

 showed no trace of a siphonoglyph. In 

 sections of two others only oite siphonoglyph 

 was found in each, placed ventrally. The 

 wall of the oesophagus is wrinkled longitudi- 

 nally, though there are no such folds as are 

 characteristic of the oesophagus of Charisea. 

 The mesenteries may be divided into two 

 groups. The first comprises the eight pri- 

 mary mesenteries. These exhibit no special 

 peculiarities (fig. 11). Each bears a much 

 convoluted mesenterial filament with a me- 

 dian glandular and two lateral ciliated lobes 

 above, and one only, the median, below ; 

 also a gonad in its oral half. The basal muscle is so folded as to 

 be fan-shaped in cross section. The main longitudinal muscle band 



is very strong, and is placed nearer the 

 free edge than the base of the mesentery. 

 It is adnate to the mesentery for its inner 

 half only, the outer half being free. 



The second group is composed of a 

 varying nimibcr of rudimentary mesenteries 

 which occur on the inner surface of the 

 column in the region of the tentacles. 

 These are extremely small, measuring 

 only one millimeter in length. Each is 

 bent in a compound curve in such a way 

 that adjoining mesenteries are nearer to each other at one end than 

 at the other (fig. 12). This condition is correlated with the ar- 

 rangement of the tentacles, which open between the mesenteries in 

 a strictly alternate fashion (fig. 13). A cross section through this 



Fig. II. Edivardsiclla si- 

 punctiloides. Cross section 

 of mesentery. 



Fig . 12 

 sipunculoides 



Edtva rdsiella 

 Rudimentary 



mesenteries between the bases 

 of two primaries. Openings 

 of tentacles shaded. 



