tubiporim;. 



329 



of the polypes by numerous rounded apertures placed at the points 

 where the corallites are embraced by the floors (fig. 212, a and b). 



,f Y* ^t ^j / m'* i 



B C 



Fig. 212. — A, Part of a tube of Tubipora mtisica, Linn., divided longitudinally, showing the 

 openings of the canal-system of the connecting-floors into the visceral chamber of the polype ; b, 

 Part of a horizontal section taken at the level of one of the connecting-floors, showing the canal- 

 system of the connecting-floor; c, Part of a corallite of Tiibipora divided longitudinally, showing 

 the axial tube ; in the lower portion of the figure the axial tube is laid open. All the figures are 

 enlarged five times. (Original.) 



In the interior of the corallites there commonly exists a hollow cal- 

 careous tube (fig. 2i2, c), which occupies the axis of the visceral 





Fig. 213. — A, Transverse section of a corallite of Tubipora viusica, Linn., taken at the level of 

 one of the connecting-floors, enlarged twenty times, showing the tubuli of the wall ; B, Portion of 

 the surface of one of the connecting-floors, enlarged twenty times, showing the external openings 

 of the tubuli of the skeleton ; c, Fragment of the corallum of Tubipora, enlarged sixty times, 

 showing the composition of the skeleton out of spicules. (Original.) 



chamber, and is dilated and fused with the enclosing theca at the 

 level of the successive connecting-floors. This axial tube is only 



