STRUCTURE AND DEVELOPMENT OF COET,orT,ANA. 25 



which h'nes the pharynx is of an essentially identical character with the 

 ventral epidermis. It consists of ciliated cells and gland cells. But, 

 excepting a small extent of the floor immediately within the mouth, 

 where it is almost the same in appearance as the ventral epidermis, the 

 epithelium of the pharynx is much taller and comprises much more 

 numerous gland cells of very large size. Especially the folds exhibit 

 quite numerous large gland cells, of which the granular cells appear 

 very conspicuous, taking stains exceedingly well, the affinity of those 

 cells for acid dyes much exceeds that of the same kind ^of cell in the 

 epidermis. It seems that the chemical composition of the granules in 

 those cells differs somewhat from that of the same in the epidermal 

 granular cells. The folds are without doubt homologous with the so- 

 called pharyngeal folds (Magenwulste) of ordinary ctenophores (cf. Mor- 

 TENSEX, '12) (PI. 2, fig. 3, pli. f). This view is supported by agreement 

 of the general macroscopical appearance, and also of the structure of 

 the epithelium of the folds (cf. Chun, '80, PI. 8, fig. 15; PI. 3, fig. 5). 



In the pharyngeal cavity I have often met with exoskeletons of 

 small amphipods or isopods, sometimes in small fragments and at other 

 times in the complete state. Evidently, the soft parts had disappeared 

 by the digestive function in the pharyngeal cavity, and in the function 

 the secretion from the gland cells of the pharyngeal folds had played 

 without doubt an important part. 



At the bottom of the sagittal furrow on the pharyngeal roof, 

 is a slit-like opening elongate in that plane, which leads dorsally into a 

 short tube communicating with the infundibulum to be directly dealt 

 with (PI. 2, figs. 2, 4; PI. 3, fig. i; PI. 4. figs. 8, 13; oe). This tube is 

 compressed like the opening with the greater diameter in the sagittal 

 plane, and is lined with an epithelium consisting largely of columnar 

 ciliated cells with both kinds of the gland cells dispersed between them. 

 The columnar cells are of an uniform size and shape in all places, and 

 carry exceptionally strong cilia at their apices (PI. 4, figs. 8, 13). This 

 tube may be called "oesophagus" after Mortensen's terminology. 



Along the median transverse plane of the wall of the oesophagus 

 exist very large clear gland cells {c. g), which make the wall project on 

 either side strongly into the internal cavity of the oesophagus in the 

 form of a broad ridge, giving the cross-section of the cavity a dumb-bell 

 shape (fig. 13). The oesophagus frequently shows a few branch canals 

 (fig. 8, oe. br), which open into either the pharyngeal cavity or the 

 infundibular cavity. Further, there may be found a canal which brings 



