•16 Mr. I\. Kiikpatrick on 



tubules, and the niassos of cell.s filling them would probably 

 be ectodonnal do\vnj;rowths as in lleliopora (G. C. Bourne, 

 Phil. Trans. 1905, vol. 186 B, p. 45")). But these are large 

 assumptions to make, seeing that neither thread-cells nor 

 zooids have yet been found. 



Canon Norman has sent me a valuable reference to a paper 

 by H. A. Nicholson and A. H. Foord, "On a new Genus of 

 Devonian Corals," in Ann & Mag. Nat. Hist. 1886, (5) xvii. ; 

 pi. xvi. fig. 5 shows a tangential section of Rhaplndopora 

 {ChaHete.fi) stromatoporoides (Roomer), from the Middle Devo- 

 nian of Gerolslein in the Eifel. The figure shows a polygonal 

 reticulation with tubercles at the nodes and with tabuUe 

 perforated at the centre and marked with radial sutural lines 

 {cf. my figure, /. c. pi. xv. fig. 13^ Some figures of Monti- 

 cuUpora also, in Nicholson's ' Palseozoic Corals,' notably 

 pi. i. fig. 1, of M. moniliformis^ show marked resemblances to 

 Merlin. The walls of the tubules in Merlia are uiiilaminate, 

 however, and neighbouring tubules have a single common 

 wall (as in the Chsetetidse). 



Prof. Weltner mentions in his paper that possibly the 

 siliceous sponge is a " Raumparasit " on the calcareous 

 structure and that the sponge might be found separate. 

 At present I am doubtful as to the real significance of the 

 association of these two elements in Merlia, and it would be 

 premature to express a definite opinion. I think, however, 

 that the association is by no means an accidental one. I 

 liave found the two together, with one unimportant exception, 

 in all the material examined, i. e. in over one hundred speci- 

 mens. In an extremely small and young specimen, forming 

 a little red spot about a millimtere in area^ the young and 

 very slender calcareous meshes are covered over by the young 

 S|)onge. The calcareous partner grows by the spreading of 

 a thin basal expansion, and slender ridges extend along this 

 floor from the nodes of the already-formed meshes, and meet 

 so as to form the youngest meshes, which are at first incom- 

 plete polygons. The exception referred to above was that of 

 an old crust of Merlia, dead and washed out, so that sponge- 

 pellicle and spicules, which had very probably been present, 

 had disappeared. I was surprised at not finding more 

 specimens in this condition. 



I have examined immerous other sponge incrustations, 

 especially red ones, but have not yet found by itself the 

 siliceous partner of Merlia. 



The sponge on the surface of Merlia has a tough semi- 

 transparent cctosome. I failed to detect oscules or ostia in 



