262 
VAUGHAN : CLISIOPHYLLUM INGLETONENSB. 
within the nucleus and, for the greater number, reaching the mesial 
plate. At the outer boundary of the nucleus, the lamellae are strongly 
thickened and short additional lamellae are intercalated, thus increasing 
the fineness of the reticulation within the nucleus. 
The concentric intersections within the nucleus are very closely 
set and cross many lamellse with continuous curvature — indicating 
tabulae without discontinuities. 
Within the aureole, however, the concentric intersections " jump " 
in passing a lamella — indicating inter-lamellar vesicles. 
[Within the nucleus of most fully grown specimens, there is a 
second zone at which the lamellse are thickened and short intermediates 
intercalated (see Fig. Id.).] 
The mesial plate has always a well-marked primitive streak and 
is exceptionally thickened ; the ends of the lamellae are firmly attached 
to it, producing the peculiar " centipede " appearance (characteristic 
also of Carcinophyllnm). 
Horizontal section at earlier stages (Figs. 16, Ic) : — 
The inner wall is very thick and formed by root-like outgrowths 
from the major septa ; the minor septa are almost embedded in the 
junction of these processes. 
The external area is very narrow, but essentially septate, although 
here and there the septa are discontinuous. 
Within the central area, the lamellae are close-set, thick and ir- 
regular, but firmly attached to the mesial plate. 
In the youngest stage figured (Fig. Ic), there is no aureole ; con- 
sequently the central area is typically Carcinophylloid, and this resem- 
blance is heightened by the presence of 30 thick septa. 
Fig. 16 shows a later stage in which the aureole has been developed. 
Vertical section at adult stage (Fig. le) : — 
The epitheca is composed of thin wavy vertical layers ; lacunae 
are frequently developed within the thickness of the epitheca, and 
especially at its junction with the theca. 
The theca is a thick solid band, minutely prismatic. 
The external area is composed of several rows of vesicles elongated 
vertically. 
The medial area contains broad distant concave tabular vesicles 
which lie more or less horizontally. 
The aureole of the central area is mainly built-up of layers of 
vesicles which dip steeply outwards. 
The nucleus shows close-set, steeply-peaked vaults, one within 
and under the other as in a Carcinophyllum. 
The mesial plate is continuous from base to summit. 
GENERIC CLASSIFICATION = 
I. Comparison with Carcinophyllum Thomson. 
As a typical species of Carcinophyllum, I select C. mendipense, 
Sibly (Q.J.G.S., Vol. 62 (1906), p. 369 and PI. 31, Fig. 4); 
this species is well known to me, and appears to agree in 
generic characters with the geno-type — C. kirsopianum Thorns. 
(Proc. Phil. Soc, Glasgow, Vol. XIV. (1883), PI. XII., Fig. %a). 
Our species agrees with Carcinophyllum in structure of nucleus 
and mesial plate, as well as in the thickened septa and inner wall. 
It differs in having a septate external area and an aureole. 
