KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 32. N:0 I. 103 



It is in the top of the branches that the 3'oungest calicles grow out (f. 32). Their 

 thiii edges are regularly circular and sraooth (pl. xi, fig. 3) and the first sign of change 

 lies in a curious plication of the thecal edge, only a single one, but visible in several 

 calicles of the same level and in all dii^ected in the same way. Next (f. 33) the edge is 

 incrassated and twelve nodules begin to appear on it, first irregularly, then (f. 34) ordinated 

 regularly around the aperture, like rounded balls covered with small warts. These three 

 calicular forms are from the same specimen. The next, the complete stage, (fig. 35) is 

 taken from another specimen found at Ryssnäs, Fårö. The tubercles are sniooth and the 

 septa, which were not visible in the next preceding stage, are at last formed showing their 

 spines in twelve rows. The tubercles should not be taken as belonging to the septal 

 apparatus as they are histologically identical with the baculi which surround them as 

 coenenchyma. The same tale is told through a section as in pl. xi, f. 4. The calicles in 

 the youngest stage, immersed in the central stratum, are of the most elementar character 

 with regular horizontal tabultp and without any septa. It is quite the same when they are 

 (fig. 2) on the verge to enter into the bacular coenenchyma. There is an indication of a 

 sort of columella in them in the centre of the tabula. In fig. 1, pl. xi, we see the complete 

 change in the arising of scarce, blunt septal spines, as it seems emanating directlj' from 

 the inner side of the theca without any lamella. 



The aspect of the tahulce is also changed, they are thinner, closer and more irregular, 

 wavy or concave, when then calicles are more fully developed. Pari passu with the changes 

 in the calicle succeed the alterations of the coenenchyma. Of its two transfer mations we 

 find the simple, vesicular to be the first. It is of the most elementary nature (fig. 4, pl. xi), 

 small convex, equal-sized lamelhx' as in some Proporae, for instance Prop. conferta, and 

 like this without the least vestiges of vertical elements. On the surface it presents the 

 aspect as shown in pl. x, figs. 32 & 33. The second modification of the coenenchyma 

 which arises, so to sa}', suddenly, is entirely composed of that vertical element for which 

 I have proposed the name of baculi. They are evidently of equal structure witli the 

 rods which make up the sceleton in several other corals as for inst. in Heliopora or 

 scattered in the coenenchyma of Prop. speciosa. These baculi of Diploepora lie closely 

 packed alongside each other with distinct lines of separation and this part of the coenen- 

 chyma thence receives a streaked appearance. A single baculus varies in length from 

 0,8 mm. to 0,5 mm. and its diameter is 0,3. In a transverse section (pl. x, fig. 37), 

 where they lie arranged as a mosaic paveraent, they have an irregularly polyedric 

 outline and a radiated surface, the radii diverging all round from the centre. This 

 stratum forms a tuberculous surface as seen in pl. x, fig. 35. In a longitudinal section 

 they have the formerly described feathery appearance with the fibrillai on both sides 

 directed upwards from an axial line. The nodules afound the calicles are exactly of the 

 same nature, only a little larger (pl. x, f. 37, pl. xi, f. 1) and corapose the whole theca. 

 This must far down have changed from its primarily simpler state, when it was environed 

 by the vesicular coenenchyma as in fig. 32, pl. x. In the section pl. x, f. 38 it has 

 acquired the baculi and from some of them prolongations like septa go towards the centre. 

 But it is there environed by a vesicular coenenchyma with traces of some baculi beginning 

 to appear. 



