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1 
d 
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gesied as features of close relationship to the genotype: 
pores of both walls regularly and closely arranged in 
quincunx; the inner wall with stirrup pores at the line 
of each septum and with further rows of pores in each 
intersept; outer surface without vertical flutings. The 
presence of a coarser net supporting the inner wall, as 
in retezona, does not indicate more than specific dif- 
ference, because we find hybrid forms grading between 
this species and ajax. 
On the other hand, features suggestive of generic 
difference are fluting of the outer surface, arrangement 
of outer wall-pores in isolated rows instead of in regu- 
lar quincunx, absence of stirrup-pores in inner wall, 
and presence of projections from the inner wall into 
the central cavity (other than irregular tissue in the 
central cavity near base, which may perhaps be an 
occasional senescent feature). 
Spitz of Ajacicyathus ajax, etc. 
The spitz, as of all members of the family, appears 
to be of Alphacyathus type; it is therefore for purpose 
of exact identification necessary to find it attached to 
a greater or less length of the cup in which adult spe- 
cific features are developed. and this is seldom possible. 
as the spitzes are usually broken off; one is therefore 
often compelled to compare notes between a poorly 
preserved attached snitz and a well preserved detached 
one. SC 
Our results agree very closely with those of Okulitch 
described in his 1935 paper. He says, “An Archaeo- 
evathid ‘starts growing as a simple, perforate cup,” 
with which we agree: but when he says, “The pores 
are of about the same size as in the adults,” we may 
say that in our specimens there is a tendency for the 
pores of the lowest part to be obscured or irregularly 
scattered. and to be smaller than in the adult. He then 
savs, “After a while a single septum appears. It may 
disappear and reapvear again in the same or another 
position in the cup or grow uninterruptedly.” . This 
descrintion is not reallv inconsistent with ours, viz.. 
that the septal structure commences typically as radial 
hars rather than vertically extended “septa.” Okulitch 
further says, "Tt is clear that the inner wall does, not 
make its appearance simultaneously with the outer wall 
and the septa, but is a subsequent development. depend- 
ing on the growth of septa”: our results confirm this. 
„but as regards his statement, “The inner wall is not cup 
shaped. as heretofore supposed. but is a hollow tube 
or truncate cone open at both ends,” we are not quite 
sure on this point, as a few of our specimens annear 
to indicate a closure or plugging at the lower end. 
These. however. are minor points, and as already 
stated. aur results agree verv closely with Okulitch’s. 
Our most complete specimens measure from 1/10 to 
1/4 mm. diameter just above the hemispherical cap 
and Okulitch says his were: “seldom exceeding } mm.” 
= so that we were working with material of about the 
same dimensions. 
i 
We have not noticed any particular persistence of 
a stage of 1, 2, 4, 6 or any other defined number of 
vertical rows of septal bars, and have no reason to 
suppose that these follow any other plan than indefinite 
increase in pace with the expansion of the cup, which 
applies also to the septa formed from these bars. 
Taylor gives sections and descriptions of young stages 
of archaeos, but his material did not show stages under 
1 mm. diameter, being mostly from the less favorable 
occurrence at Ellis Hill. 
Our results yield no confirmation of Ting's descrip- 
tion (l.c., p. 346/7) of the first septum and inner wall 
as arising by invagination from the outer wall. 
A number of etched sections of young spitzes from 
various points of view are shown in Plate XLIV, Fig. 
178, and in Plate XLY. 
By far the commonest archaeos at the Ajax Mine 
are, Ajacicyathus ajax and retezona and Cyclocyathus 
trachealis and the majority of spitzes may fairly be . 
presumed to belong to these forms, but as distinctive 
specific features do not seem to appear till a diameter 
above about 2 mm., it is very difficult to be certain 
of the specific identification of the smallest spitzes. 
In Plate XLIV, Fig. 178, is shown an instructive 
small spitz of Ajax-retezona type; at (A) is the surface 
as first exposed, the papilliporous condition of the 
pores there shown is often seen in small specimens 
of a few mm. diameter and often seems to be lost in > 
older ones. The exposed transverse sections above and 
below are shown in B, which is 1$ mm. diameter and 
shows four septal bars and both porous walls, and in 
C, which is 1/3 mm. diameter and shows a single porous 
. tube. The specimen was then ground off longitudi- 
nally and re-etched, D. to graze the inner wall; and: 
the process repeated, E, to show a median section, with 
the inner view of inner wall exposed. The specimen 
shows that the spitz originates as a simple conical 
norous tube, septal bars and porous inner wall being 
added when the diameter has increased to about 2/3 
mmn. 
mm . 4 9 
In Plate XLV, 
Fig. 179, is shown a series of trans- 
verse sections of a similar spitz ending below in a 
hemispherical cup 1/5 mm. diameter; 
1/3 mm.. and the inner wall at 4 mm. 
rods appear at 
tn Plate XLV, Fig. 180, is shown a very small spitz. ` 
At A is shown the appearance when first exposed, 
and at B and C the result of further grinding away of 
The fragment is broken off and somewhat. 
crushed above, D being an oblique transverse section ` 
produced by grinding off a little more of the specimen 
mm. Further longitudinal grinding 
matrix. 
to a diameter of $ 
and etching gave Figs. E and F. The tip of this little 
specimen is the smallest complete one we have found: | 
measuring only 1/10 mm. just above the tip; from ' 
this it continues as a single conical tube, irregularly 
rods ‘and inner wall 2 
The rods develop rapidly into septa, MORO are | 
porous, until at under 4 ram, 
appear. 
- well established at 2 nim. 
