FRENCH GONIOPORJE. 131 



Within the wall and distinct from it are seen 12 radiating portions of the septa as abort 

 crisp plates, with jagged edges round the centre. Peripherally they run into a reticulum, 

 which is composed of the forkings and fusions of the septa before they abut against the wall. 

 There are thus, in reality, 18-24 septa, some free and others fused, when counted close against 

 the wall -ridge. 



The apparent peripheral ends of the 12 central plates frequently send out T-pieces, which 

 tend to unite to form a synapticular ring round the fossa, and are the points of fusion of 

 the tertiaries. An open columellar tangle fills the base of the fossa, and from it an irregular 

 ring of pali with a central tubercle arises, but the ring, though frequently consisting of five 

 points, is seldom regular or symmetrical, and the relations between septa and pali are very 

 irregular. 



In the sections, both transverse and longitudinal, the calicles can be traced through the 

 stock. The reticulum is delicate, and shows a tendency for the horizontal elements to be 

 tlaky while the vertical trabecule are continuous and thread-like. 



This form from Gironde is very like some of the extreme forms of the Paris Basin ; forms 

 which look at first sight exactly like Pontes, but which have a columellar tangle, and when 

 the notches in the walls are counted, show that there were more than 12 septa (cf. G. Paris 

 Basin 11, and Table IV. G, p. 182). 



There are two very beautifully preserved specimens, but unfortunately their original 

 surfaces are rubbed off. They are obviously the same coral, and are of no small morphological 

 importance in the genus ; for they show the . meaning of the forking abutment of many of 

 the septa against the wall, viz. that the true number is 24, and that the 12 radial plates round 

 the centre are merely the inner ends of the septa, perhaps the homologues of the pali, rising 

 at the points of septal fusion. I can see no argument against this interpretation, and if 

 correct, this septal system is a modification of the typical formula of Goniopora. The small-_ 

 ness of the calicles increases the resemblance of the coral to a Porites. 



As stated in the observations to the Paris Basin specimens, it is possible that the filling 

 up of the fossa with a close septal reticulum may be a protection against sand or mud, a 

 deposit of which might easily weigh down the delicate skin into the skeletal interspaces, if 

 the latter were large. 



Specimen a (II. 2185) has two small portions of original surfaces in which the wall-thread, 

 and the jagged edges of the septa, are perfectly preserved. One of these has been photographed 

 on PL IX. fig. 5. 



Both specimens show the borings of molluscs, the shells of which are still visible in a. 



a. Labelled Astrcca Ellisiana Def. Geol. Dept. K. 2185. 



b. „ Porites iwrnstans Def. ,. „ R. 2184. 



