28 T. KOMAI : STUDIES ON TWO ABERRANT CTENOOHORES 



towards the body parenchyme through the rosettes. The second kind 

 is tall, non-ciliated and is made up of cells of large sizes which are 

 more or less vacuolated and often amoeboid in character. No rosette 

 occurs in this kind of epithelium. This epithelium performs intracellular 

 digestion of food material and possibly excretory function too. For 

 the sake of description, I shall call the first kind of epithelium the 

 ciliated epithelium and the second the vacuolated epithelium. The 

 ciliated epithelium constructs the ventral walls of the tentacular, sub- 

 pharyngeal and subtentacular canals as well as both the dorsal and 

 ventral walls of the peripheral branchlets. The vacuolated epithelium 

 lines the lateral walls of the perradial, subpharyngeal and subtentacular 

 canals. It also occupies the lateral sides of the canalar branchlets, 

 where it forms a ridge-like tract on each side (PI. 4, fig. 15; v. c). The 

 vacuolated epithelium develops to the utmost thickness on the dorsal 

 side of the tentacular canal, where it consists of extremely bulky cells 

 enclosing nuclei also of large size. 



The third kind of epithelium, which may be called the "palisade" 

 epithelium, because of its appearance somewhat reminding one of the 

 palisade tissue of the plant leaf, is found on the dorsal side of the 

 subpharyngeal and subtentacular canals (PI. 5, fig. ii; pal). It presents 

 a character practically between the above two kinds. It is fairly tall, 

 slightly vacuolated and distinctly ciliated, but contains no rosette; it 

 consists of tolerably large columnar cells closely juxtaposed. Since it 

 is provided with both the cilia and the food-vacuoles, it can perform 

 without doubt both of the functions of the two kinds of the epithelium 

 previously mentioned. 



The ciliated rosette, which occurs in the ciliated epithelium of the 

 canal system, is of an identical structure with that of ordinary ctenophores 

 (Chun, '80, PL 16, figs. 37, 38; Hertwig, '80, PI. 21, fig. 8). It is 

 composed of ciliated cells, small in size and pyramidal in form, arranged 

 in two rings, superposed one upon another (PI. 4, fig. 17). The inner 

 ring of the two {in.r) consists of cells usually eight in number arranged 

 around a small central space. The cells carry very long and tliick cilia 

 which lie imbedded in the gelatinous parenchyme tissue. Tlie tissue 

 appears to be of more fluidal consistency in that particular part, being 

 .stained more weakK'. The outer ring {on. r) is likewise made up of 

 eight cells or .so, and has usually a greater diameter than the inner 

 ring, so that, the ring often shows its i)erii)hcral parts outside the margin 

 of the inner ring in the front view of the rosette. The cilia borne by 



