112 CARBONIFEROUS CORALS AND BRACHIOPODS 
that any particular type of calyx is found associated with 
every stage of difference in other respects. 
Again, the external ridges vary from mere ornamental 
rings at fairly equal and close intervals up to a few strongly 
pronounced, funnel-shaped projections which clearly 
indicate the fact that they were the edges of earlier calices. 
The figure* of Strephodes multilamellatum, given by 
McCoy, agrees very closely with PL 31, Fig. 2a of the 
Palaeontographical Monograph which is specially drawn 
to illustrate the external form of C. Stutchhuryi ; but, 
seeing that McCoy’s species is included by Ed. and H. 
under G. Murchisoni, it is unnecessary to dwell further 
upon the uselessness of the external annulation as a spe- 
cific character. The slight compression noticed under 
C. Murchisoni is a common character of all elongate forms, 
and is not constant, even in the same individual. 
The differences to be observed in the number, thickness 
and ratio of the septa are rather apparent than real ; in 
all specimens the septa are markedly alternate, being made 
up of two series ; all the septa forming the first series reach 
the centre, whilst all those of the second series stop short 
at approximately the same distance from the centre. 
(This is quite clearly shown in the figured specimen of 
C. Murchisoni and the fact is brought out in the drawing, 
though apparently contradicted in the text.) Again, when 
the septa are quite thick, their number is usually exactly 
the same as when thin (e.g., there are sixty-three primary 
septa in the type specimen, and I have counted the same 
number in fifteen other specimens which show every 
variation in thickness). The ratio of the diameter of the 
whole section to that of the inner area, radiated by a 
single -series of septa, is extremely variable and of no value 
whatsoever as a distinctive character. 
So far I have dealt with all the characters upon which 
the two species were originally separated, and it seems im.- 
