106 Prof. G. Lindstrém on the 
pancies may be reconciled in the following manner. We have 
given different values to the septal orders, viz. :— 
The primary septa of Pourtalés are my tertvary septa. 
The secondary _,, 4 o primary 5, 
The tertiary iy, 55 3 secondary 4, 
Those large septa which are enclosed by a pair of other 
septa I regarded as the primaries. I was led to this by what 
I had learnt from Balanophyllia Goésti (Actin. Atl. Ocean, 
pl. iii. figs. 40-42), in which it is evident that the primaries 
are enclosed within two of the next succeeding order, that is 
the secondary, so that there are two secondaries for each of 
the primaries, or in all twelve, as seen on plate ii. fig. 41, in 
Actin. Atl. Ocean. On comparing smaller and larger speci- 
mens of Schizocyathus I cannot but think that I was right in 
arranging the septa as I had done. The primaries of Pour- 
talés are easily recognizable by their position inside the distinct 
line which is so clearly visible on the wall outside, and along 
which the coral splits. Now in the smallest specimens, 
scarcely 1 millimetre in length, what I have called primaries 
are the largest septa developed, and the primaries of Pour- 
talés, my tertiaries, are just beginning to appear. 
Prof. Duncan further says (p. 367), ‘that there are no septa 
in Lindstrém’s figure (pl. 1. fig. 27) in the position of the 
primaries of Pourtalés.’”’ It is true that they are not visible 
in the specimen figured, because their growth has ceased or is 
retarded, as is shown on the same plate (fig. 26). But I have 
other specimens, in which these septa, though short, are as 
plainly seen on a level with the others in the calicle as in the 
original specimen of Pourtalés. 
As to my remark on the composition of the septum of three 
distinct strata or lamine, one central enclosed within two 
lateral ones, Prof. Duncan makes a quasi-quotation from my 
paper, from which it might be implied that I have contradicted 
myself or partially admitted the truth of the old opinion. 
After briefly stating my views he adds that, ‘ He [Lindstrém] — 
candidly admits that the two lamin are to be seen in some 
fossils”” (Ann. & Mag. Nat. Hist. Dec. 1883, p. 367). 
I said, consistently with my view of there being three 
structural elements in the septum, that old and weathered 
specimens look just as if they had septa consisting only of 
two lamine; but this is only owing to the central or original 
lamina having been removed by solution and its place left 
empty (Actin. Atl. Ocean, p. 17). It is just this structure of 
the septum which is one of the chief points that link the 
