lg Dr. Asajiro Oka: 



middle of the cells. The cilia are long and delicate. They are 

 from five to ten on each cell, attached to the more or less convex 

 outer edge, and when fully extended they are more than twice 

 the height of the cells. 



The transverse vessels are three in number and are all of the 

 same size. They are about twice as wide as the fine longitudinal 

 vessels and contain delicate muscle fibres (PL II., fig. 12, tr. v.). 

 When contracted the branchial sac is always strongly constricted 

 along these vessels. The zone devoid of stigmata along the 

 dorsal edge of the branchial sac is very narrow, so that the rows of 

 stigmata of one side appear to pass over to the opposite side 

 without much interruption. The median dorsal vessel also 

 contains muscle fibres in its walls and is found strongly contracted 

 in most zooids. 



Endostyle. The endostyle runs along the ventral edge of the 

 branchial sac (PL IL, fig. 8). It begins anteriorly at the base of 

 the branchial siphon immediately behind the peripharygeal band 

 and runs backwards to the base of the sac, ending at a short 

 distance from the oesophageal aperture. The ends are bluntly 

 conical, otherwise it is of the same width throughout. In the 

 greater part of its course it forms a series of minute dorso- 

 ventral undulations. Whether or not this is a result of contrac- 

 tion of the branchial sac I am not able to say. At any rate, in all 

 the zooids examined by me the endostyle invariably showed this 

 character. The anterior end of the endostyle is turned inw^ards 

 forming a sort of blind sac at the point of bending (PL IL, fig. 7, 

 end.), so that in certain sections passing through this region the 

 endostyle appears as a canal. 



The endostyle is a groove with greatly thickened sides 

 formed of columnar epithelium, w^hile the base is covered with 

 somewhat shorter cells (PI. IL, fig. 14). The summits of the 

 edges are continued up as lip-like folds. A tract along each 

 side and the base are richly ciliated. As shown in the figure 

 several kinds of cells can be distinguislied in the wall of the 

 endostyle. Those forming the base stain deeply with haemalaun 

 and are provided with very long cilia, reaching, if not exceed- 



