2i6 TABULATE CORALS. 



ly-divided axial tube. In long sections (fig. 30, a) the septa 

 present different appearances in different parts of the slide 

 (precisely as in Favosites), according to the inclination of the 

 plane of the section as regards the axial plane of the corallite. 

 Where the section cuts throusfh the axis of the visceral cham- 

 ber, the septa are only seen as lateral spines directed inwards 

 from the bounding walls of the tube ; where the section is to 

 any extent excentric, the cut ends of the spiniform septa come 

 into view as rows of circular spots ; and where the section 

 coincides with the wall of the corallite, the cut bases of the 

 septa look like rows of light spots in the darker-tinted scleren- 

 chyma which surrounds them (see fig. 30, a). The most strik- 

 ing feature in long sections, however, is that of the infundibuli- 

 form tabulse arranged in a succession of invaginating cones, 

 which give rise centrally to a distinct axial tube. This axial 

 tube seems to be intersected by occasional prolongations of 

 the tabulae inwards ; and owing to the flexuous condition of the 

 tubes, it is never laid open continuously for any distance. On 

 the contrary, any long section, as a rule, cuts the axial tube 

 over and over again with varying degrees of inclination, so 

 that we are presented with repetitions of the obliquely-divided 

 tube, surrounded by the cut edges of the concentrically-dis- 

 posed ensheathing tabulae. Lastly, both long and cross sec- 

 tions show that the connecting-processes afford a direct com- 

 munication between the visceral chambers of contiguous tubes, 

 and that the progressive walling off of the visceral cavities of 

 the polypes by the production of tabula is accompanied by an 

 extension of these structures into the connecting-processes, as 

 these are successively rendered useless. It only remains to 

 add that Milne-Edwards and Haime speak of this species as 

 being remarkable (Brit. Foss. Cor., p. 163) "for the existence 

 of a delicate transverse lamina which passes through the con- 

 centric infundibula, and is shown by a transverse section of the 

 corallum ; " but I can find no traces of such a structure, and 

 do not feel sure if I rightly understand what structure they 

 refer to. 



