466 



TAKU KO MA I : 



than that between subpharyngeal ribs, the ratio being usually 5 : 4 and 

 sometimes 3 : 2. The subtcntacular ribs are almost always shorter in 

 varying degrees than the subpharyngeal ribs, the difference of length 

 being very slight in large individuals but fairly marked in the smaller. 

 As wHl be seen from the following table, the degree of difference in 

 the length of the two kinds of ribs is, roughly speaking, inversely 

 proportional to the size of body. 



Body length. 



Ratio of the length of 

 subtentacular rib to 

 that of meridional 

 canal. 



Ratio of the length 

 of subpharyngeal rib 

 to that of meridional 

 canal . 



Over 30 mm. 



20-30 mm. 

 15-20 mm. 

 5-10 mm. 



(Subpharyngeal rib on 

 subtentacular rib). 



3:4 



2:3 

 Less than 1 : 2 



ly slightly longer than 



4: 5 

 4:5 

 2 : 3 



The comb-plates are very numerous and closely set ; I have counted 

 as many as 200 of them in each rib of an individual of 62 mm. length. 

 The area of sabre-shaped cilia on the pharyngeal wall is not prominent. 

 The cilia are small, measuring 25 fi in length and 2.5 ft in breadth on 

 the average. The meridional canals are provided with a number of 

 side-branches, which, in large specimens, repeatedly divide and present 

 a dendritic appearance ; but no anastomosis occurs, excepting a few 

 near the oral margin of body. The level of the origin of side-branches 

 from meridional canal differs in the same way as MOSER has described 

 for B. cucumis (1908, p. 24, figs. 1, 2) : on the perradial side, the 

 branches arise from the parts near body-surface, and on the interradial 

 side from deeper parts of the canal. The pharyngeal canals never 

 send out branches. The marginal canal of oral aperture sends out 

 numerous branches on both aboral and oral sides ; some of these, on 

 the narrower sides of body, join with the side-branches of meridional 



