288 ^^6 American Geologist. November, isii* 
which at that stage is far from being the case, as has been re- 
cognized by authors following Kunth. How the first few 
minor septa are introduced is not certainly known to me be- 
cause in the very early growth of the cell they are developed. 
Their appearance later is not in the same manner as the major 
septa as was before supposed. 
The four major septa designated as primary septa, or re- 
spective!}' cardinal septum, counter septum and alar septa, 
are supposed to develop simultaneously, then four more major 
septa appear each bisecting one mesenterial loculus between 
two primary septa. Next four more major septa divide four 
loculi, i. e. the loculus on either side of the cardinal septum 
and one on the farther (posterior) side of each alar septum 
are divided ; thence four more major septa appear in the same 
manner as the last, and so on, dividing always the loculi on 
either side of the cardinal septum and on the posterior side of 
the alar septa, Kunth has described this manner of develop- 
nient for both major septa and minor septa. But after the first 
major septa have developed, then each new major septum de- 
velops from a minor septum, following which two minor sep- 
ta, one on either side of the new major septum appear, and of 
these the minor septum next to the primary septum becomes 
a major septum, and so on. Notably, the major septum ap- 
pears before the minor septum back of it and the permanent 
minor septa are really intercalated between and not developed 
alternatively wath the major septa, (fig. 8, plate XVII). 
This mode of growth is observable on the inside of the cell 
and also on the furrows on the outside in the theca. It is not 
peculiar to this species or genus. The figures by Kunth re- 
present the major septa correctly but the minor septa must be 
differently interpreted, (see figs, 9, 10, plate XVII). I have 
not succeeded in observing the septal increase sufficiently in 
the initial stages, but most probably it is like the later devel- 
opment, (see figs. 11, A-D. plate XVII). 
The major septa are developed before the minor septa al- 
though neither the first order (major) nor the second order 
(minor septa) develops simultaneously, but the two kinds de- 
velop pari passu as described. Theoretically each four major 
septa developed simultaneously and each four minor septa 
correspondingly, but the growth is not necessarily so regular 
