430 MR. J. J. SIMPSON ON THE 



The branches arise from the calcareous internodes, generally 

 one from each ; but as many as three sometimes occur on one 

 internode. In most cases there is a considerable calcareous 

 portion before the first node ; but this is often so reduced that 

 the branches seem to arise with a horny part. In other places, 

 owing to the origin being close to the node, the branch seems to 

 arise from it. 



Cross and longitudinal sections of a calcareous part, 1 centim. 

 in diameter, were ground to show the internal structure. There 

 is a distinct radiate appearance from centre to periphery. About 

 1'2 millims. from the centre there is an undulating line which 

 corresponds to the grooves on the outside, but in this case they 

 are fewer in number. Towards the circumference, and at a 

 distance similar to the first, there is another almost identical 

 line with a greater number of undulations, but still fewer than 

 those on the periphery. These wavy liDes doubtless correspond 

 to what were previously the external surfaces of the axis. The 

 central portion is quite homogeneous in character and is 

 apparently amorphous ; but in the younger part it is evidently 

 composite, the small particles giving different extinctions. It 

 cannot be argued from this, however, that the axis is sclerogorgic, 

 because the boundary-lines of the different parts may be the 

 organic remains of the dead calicoblasts. At the same time, it is 

 important to note that in similar sections of Melitodes little or 

 no difference could be found. This subject is worthy of further 

 study, seeing that it is used as a basis of classification. When the 

 internodes were decalcified, there was a considerable residue of 

 organic matter. 



The coenenchyma is very thick (PI. 43. fig. 3), in some parts 

 2'5 millims. It is supported by small, densely-packed spicules of 

 various shapes, which make it very brittle; and hence the mark- 

 edly deciduous character, so often referred to. On the surface 

 there is a layer of spicules q^rranged so that all their warty 

 ends project outwards, and so form a specially hard protective 

 layer. Owing to the enormous preponderance of spicules, it was 

 almost impossible to cut sections. Decalcification resulted in a 

 complete collapse of the coenenchyma. 



The nutritive system consists of (1) a longitudinally arranged 

 set of canals, one corresponding to each groove on the axis ; 

 (2)- a branching system throughout the coeneuchjma connecting 

 these with the individual polyps. These canals have soft flaccid 



