224 
Proceedings of the Royal Society 
3. General structure of the corallum of Syringopora. — The genus 
Syringopora, Goldfuss, is one well known to naturalists, and its 
leading structural characters have been fully described by myself, 
(“ Palseozoic Tabulate Corals,” p. 207). As my object on the present 
occasion is simply to compare it with Tubipora , it will be 
unnecessary for me to do more than merely to draw attention to 
some of its more striking characters. The corallum in this genus 
is composed of fasciculate cylindrical calcareous tubes, which are 
placed at variable hut slight intervals, and diverge slightly as the 
surface of the colony is approached, owing to the interpolation of 
new tubes. The visceral chambers of adjoining corallites are 
placed in direct connection by means of hollow, usually cylindrical, 
horizontal connecting-processes or tubes. These connecting-tubes 
are generally quite distinct from one another, and placed at toler- 
ably regular and moderately distant intervals ; but they are some- 
times developed in successive whorls (as in S. verticillata , Goldf.), 
or the verticils may coalesce so as to give rise to almost uninter- 
rupted horizontal connecting-floors (as in S. tabidata , Yan Cleve). 
In this latter case, the mere external similarity of the corallum to 
that of Tubipora is very striking. 
As regards the internal structure of the corallites of Syringopora , 
the visceral chamber of each tube is always subdivided by a 
remarkable and well developed system of tabulas. These tabulse 
are, typically, more or less infundibuliform, and they generally 
become invaginated in such a manner as to give rise to a central 
cylindrical tube, which occupies the axis of the visceral chamber 
(fig. 3, a). This axial tube, however, is in no respect a distinct or 
separate structure; but it is simply a central space left by the 
union of funnel-shaped tabulse, and often broken up by the 
inward prolongation of these across its central cavity. In all the 
species of Syringopora , also, the corallites are provided with a well- 
developed system of septa. The septa (fig. 3, a and b), are entirely 
of the “ Favositoid ” type, or of the type of the septa Porites, being 
never lamellar, but having in all cases the form of slender spines 
arranged in vertical rows. They never extend more than a 
limited distance into the visceral chamber, but they vary in length, 
the larger species seeming to have about twenty rows of septal 
spines to each corallite. 
