﻿PAPILLATE MONTIPOR^. 75 



55. Montipora lanuginosa. (PL XIII. ; PL XXXII. fig. 20.) 



Description. — Corallum explanate, thin, translucent, freely expanding or encrusting, 

 creeping or drooping over former growths or other corals and calcareous algse, the stocks thus 

 forming great irregular mounds. By creeping up and enveloping Serpula tubes, or projections 

 of the substratum, short irregularly bent branches are formed. There are thus smooth 

 expanding portions alternating with irregular mounds of knobs and crooked lobate processes. 

 These irregular areas may rise into almost spherical lobulated masses like the inSorescence of 

 a cauliflower. Epitheca very irregularly developed. 



Calicles crowded, less than their diameter apart. Full sized calicles in the thicker parts of 

 the corallum from • 5 to • 75 mm., much smaller in the thinner texplanate portions. The 

 calicles have no sharply circumscribed margins, and are chieiiy recognisable by the radial 

 arrangement of the septa round a fossa. Held up against the light the stars are ragged and 

 unsymmetrical. Six primaries are well developed, of which 'one, sometimes two, form 

 directives ; thin secondaries appear irregTilarly. On the under side the calicles are specially 

 minute, openijig on the smooth reticular surface j they are ©ften very irregular in shape and 

 in their septal apparatus. 



Ccenenchyma purely reticular^ when resting on an epitheca or encrusting a worm-tube it 

 forms a perfectly solid layer in contact with them. At the surface the reticulum rises in the 

 interstitial spaces into large loose papillae, which, to the naked eye, have a woolly appearance, 

 and under the pocket-lens are richly branching and have a ragged or flaming appearance. 

 The calicles seem to open between the tangle of points at the bases of these papHlse, the septa 

 being formed by the radiate arrangement of certain of the points themselves, hence the 

 absence of any sharply circumscribed margin to the calicular aperture. In the thicker parts 

 of the corallum, the papillae are somewhat more compact and often run together, giving rise 

 to small calicle-bearing nodules. On the thinner and more explanate portions, they are less 

 pronounced and more irregularly and openly branched. The under surface is always smooth. 

 The reticulum may be loose and thread-like near the margin, or solid and stony, with pores 

 and fissures, at some distance from the growing edse. 



There are two large specimens forming irregular mounds nearly 40 cm. across, and 15 to 

 20 cm. high in the highest parts. Each is composed of an irregular arrangement of thin ex- 

 panding portions, generally sloping downwards and outwards, and great shapeless nodulated 

 masses, with here and there thick, bent, finger-like processes, each encrusting the calcareous 

 tube of an Annelid. The smooth explanate parts look like old flannel, the surface of which has 

 been rolled into minute but loose knots. Both specimens are from Mauritius, and were 

 previously labelled M. tuherculosa, Lamarck (cf. p. 112). 



The two specimens present some striking differences. WhUe both have smooth flannel- 

 like portions, the nodulated portions of a are quite irregular and shapeless ; but in h, the 



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