ox MERLTA XOEMANl. 659 



had known that the pin-shaped spicules were siliceous — as, 

 indeed, they were-^I would have considered them as part 

 of a siliceous sponge growing over a Pharetronid. In January, 

 1909, mainly with the object of procuring living specimens 

 of Merlia, I spent a winter holiday at Madeira and Porto 

 Santo. After dredging for nine days off the latter island I 

 found the sponge in sixty fathoms off a little rocky islet 

 called Cima, at the S.E. corner of Porto Santo. The living 

 specimens were in the form of little bright vermilion crusts, 

 with a smooth surface. At first, when removed from 

 the water, nothing else was seen excepting the bi-ight 

 smooth patch of colour, but soon the surface sank a little, 

 and the porcelain-white skeleton network with its nodal 

 tubercles became visible, thus enabling Merlia to be distin- 

 guished from certain other small red incrusting organisms 

 brought up in the dredge, viz. a red Ectyonine sponge, a 

 polyzoan, a compound ascidian and a coralline alga. It is 

 true these latter all had slightly different shades of red, but 

 Merlia itself varied slightly in this respect. A crust of 

 Merlia broken in half showed the cavities of a calcareous 

 framework filled with orange-coloured jelly. 



Specimens were fixed in '5 per cent, osmic acid in sea- 

 water, washedj stained immediately in Weigert's picrocarmine, 

 and either graded into alcohol or put into glycerine. Others 

 were fixed in Flemming mixture, and others again in absolute 

 alcohol. 



When I catue to examine the first decalcified sections of the 

 fresh material I was expecting to find a Pharetronid sponge, 

 and great was my surprise on seeing at the surface a siliceous 

 sponge, and below the latter and in continuity with it a series 

 of separate but closely packed parallel moniliform cylinders 

 chiefly made up of large granular cells imbedded in a 

 tough transparent maltha. la specimens decalcified whole 

 the cylinders hang down from the thin surface lamina, the 

 various segments of each cylinder being united by narrow 

 central isthmuses of tissue which had passed through the 

 holes in the centre of the tabula. After a Ion or seaicli 



