404 Bahhv'ui Spencer: 



the only jnirts where ;uiy cellular structure can be detected. 

 The central tube functions, presumably, as an alimentary canal. 

 Its oral openino; is just a simple round hole in the jelly, and 

 from this a Hask-shaped tube, i^radually increasing: in size, ex- 

 tends upwards for about four-fifths of the lenijth of the jelly 

 mass (Al. 1). From the centre of the aboral end a small but very 

 definite canal arises, and from the same point four l)ands take 

 their orif^in and run down the walls of the tube, alternating in 

 position with the angles of the jelly mass (Figs. 1 and 2). One 

 band corresponds in position with the deep external groove. 

 (Fig. 4, Gl. 1.) In two of the sjnecimens indications can be 

 detected of a very finely attenuated platedike structure running 

 across to each of the four faces of the jelly from the modified 

 bands. (Fig. 4., Spt.) One of these plates corresponds in posi- 

 tion with the deep groove, but in three specimens of which 

 sections were cut I could not distinguish the faintest trace of 

 any structural differentiation representing them. There is nor, 

 the slightest indication of any canal system other than the 

 central tube. The relationship of the various structures referred 

 to are represented diagramatically in Figure 4. 



In some specimens the bands on the wall of the central cavity 

 do not extend as far as the oral opening, but in others they do. 

 Each has clearly a doiible structure, probably representing two 

 rows of cells, and they (together with the small aboral canal 

 and two special structuves to be described later) stain much 

 more deeply than any other part. In Figure 6 a small part of 

 one is shown, together with the adjacent lining of the tube. 

 The band shows no clearly marked outline of cells, only faint 

 indications of this. The protoplasm is reticulated, and when 

 stained stands out in strong contrast to the homogeneous jelly 

 in contact Avith which it lies like a ribbon. The cells, if such 

 they be, are uuich flattened out, and contain numerous rounded 

 and irregularly shaped bodies, which stain deeply am: some- 

 times enclose unstained s))herical portions. Between the bands 

 the renuiining ])art of the wall of the tu!)e is lined by a single 

 layer of extremely thin cells (Fig. (>, Gl. _) with nuclei that are 

 smaller than the dark bodies in the bands, and take stain much 

 less deeply. Tliese cells' are evidently easily displaced, as in 

 some cases they are absent, and the wall of the tuiie is actuallv 



