On the Skeleton in Corallium, Tubipora, and Syringopora. 29 
tineze, there is a repetition of the same phenomenon which has 
been previously described in the series of forms of the Gelidiex 
and Cryptonemiez, namely, that in certain forms the ramified 
ooblastema-filaments produce spores directly from their cells ; 
whilst in others these individual cells enter into connexion 
with the cells of the surrounding sterile thallus-tissue, and thus 
the formation of multicellular complexes of spores is super- 
induced*. 
[To be continued. ] 
Il.—wNote on the Structure of the Skeleton in the Genera 
Corallium, Tubipora, and Syringopora. By H. ALLEYNE 
Nicuotson, M.D., D.Sc., Regius Professor of Natural 
History in the University of Aberdeen. 
SoME time ago I published a short paper on the structure of 
the skeleton in Tubzpora, with special reference to the rela- 
tions of this genus to the Paleozoic Syringopora (Proc. Roy. 
Soc. Edinb. 1880-81, p. 219). The general conclusion to 
which I was led by a comparison between these two types 
was that, though undoubtedly similar in aspect, they were not 
really related to one another. The grounds upon which I 
based this conclusion were the following :— 
(1) ‘In the first place, there is the very important and 
remarkable difference in the minute structure of the calcareous 
skeleton in the two types in question. In Tubipora the 
corallum is made up of fused calcareous spicules, which are 
so disposed as to give rise to a universally distributed system 
of minute canaliculi or tubuli, which open on both the outer 
and inner surfaces of the skeleton by well-marked apertures. 
The size of these tubuli is comparatively so great that it is 
quite impossible that their presence could be overlooked in 
thin sections of Syringopora, if they really existed in this 
genus. Qn the other hand, the skeleton of Syringopora, as 
* I have hitherto found among the Gigartines nothing analogous to 
the third case, namely, that the cells of the ooblastema-filaments conju- 
gate with individual cells of the thallus, and then these thallus-cells de- 
velop into multicellular spore-complexes. 
+ Mr. Hickson has rightly pointed out that the term “ fused” as applied 
to the spicules of Tubipora might lead to some misconception, as actual 
amalgamation of the spicules does not take place. The spicules, on the 
other hand, are united with one another closely by their sides or projecting 
points, and it was to indicate this union only that I employed the term 
“ fused ” in my former paper. 
