Dr. R. Schifer—On Phillipsastrea, d’ Orb. 405 
species of Phillipsastrea the proper wall was wanting, but that 
an interior mural investment existed, the presence of which was 
looked upon as a generic character. This view, however, certainly 
does not hold good in the case of those species examined by me. 
Only in very rare cases, in single corallites, could I perceive near 
the outer part of the central cavity anything that would suggest 
the rudiments of a wall between the septa. These rudiments show 
in horizontal sections the same arrangement as the vesicles, but differ 
from the latter in that they have the same structure as the septa. 
These rudiments of an interior wall are only of very limited extent, 
they comprise at the most only one-eighth of the circumference of 
the calicular fossa, and are besides so seldom met with, that they 
appear to be unimportant for purposes of classification, and I consider 
them rather as abnormal structure. PI. XII. Fig. 7 shows a corallite 
in which such rudiments occur. In the same way Schliiter and 
Barrois have disproved the existence of an interior wall in certain 
species of Acervularia. 
Endothecal sclerenchyma.—The endothecal sclerenchyma which fills 
up the interseptal loculi consists of semicylindrical vesicles with their 
concave side turned downwards, which lie above one another in 
alternating rows. This arrangement is substantially the same as 
that of Phillipsastrea Hennahii, the internal structure of which has 
been described by Kunth. To illustrate the structure he has very 
aptly likened the arrangement of the vesicular tissue to that of 
“semicircular drain-tiles.”’ The figure which he gives (loe. cit. p. 33) 
will also facilitate the comprehension of the structure of Phillipsastrea 
radiata. In the inner part of the calyx, where the vesicles surround 
the central cavity, they are closer and more perpendicularly arranged, 
whilst in the outer parts of the calyx the vesicles are coarser and 
flatter (Pl. XII. Fig. 4). Itis nevertheless difficult to see whether the 
different forms of vesicles really represent a different structure, or 
whether it is merely due to the difference of angle at which the section 
cuts the axis of the semicylinder. <A section at right angles to this 
axis would give the first appearance, while the second appearance 
would be produced by a section more nearly parallel to the axis. 
The vesicles reach as far as the septa, but do not extend through 
or into them, also their minute structure is quite different from that 
of the septa. 
Tabule.—In the middle part of each corallite tabule exist. They 
extend outwards as far as the closer and more perpendicularly 
arranged vesicles, and continue through the central cavity at equal 
distances. The distances between the single tabule are a little 
greater than between the vesicles in the endothecal tissue. They 
are either level, or are slightly bent upwards in the middle, and so 
take the form of an obtuse hollow cone, with its apex uppermost. 
Both kinds of tabule are connected by gradations, and occasion- 
ally both horizontal and cone-shaped tabules may be observed in the 
same specimen. If a horizontal section is made of a cone-shaped 
tabula, we see oy a circle inside the cone cavity as on Pl. XII. 
Fig. 6, 
