﻿60 MADEEPORAEIA. 



extreme forms they are on the one hand faint white lines, on the other, ridges almost a milli- 

 metre in height. Single circular ridges may rise up round large calicles forming an open conical 

 but shallow cup. Out of groups of such slightly protuberant calicles, erect, finger-like processes 

 may arise 5 to 6 cm. high. As these thicken, thin secondary processes may again start from 

 their tops. These finger-like processes, starting from protuberant calicles, differ from the 

 cylindrical bent processes caused by the corallum-encrusting worm-tubes. Where the growth 

 of these processes or of the edge of the corallum has been hindered, either by some external 

 object, or perhaps by reaching the surface of the water, theii* tops are flat and spongy. 



There is one large specimen with wavy edges (and two fragments) representing this type. 

 It forms an irregular oval dish, horizontal, 40 by 30 cm., partly resting on the tips of a branch- 

 ing member of the same genus, M. alcicornis. This same habit has been described for 3f. pclti- 

 formis, but the two corals are quite different in the specialisation of the cronenchyma. 

 One peculiarity, after which I have named the specimen, deserves noting. The coral is in 

 aspect curiously challcy, and has all the appearance of having been dead and slightly 

 corroded when collected. As a rule, the coenenchyma in the Madreporaria is composed of a 

 smooth glistening substance ; in this case it is all of a dull opaque white, and like the 

 ordinary ccenenchyma when commencing to decompose. There is, however, no other sign of de- 

 composition, and the finest reticulum is sharp and distinct when seen under a magnifying glass. 

 Further, the branched coral {M. alcicornis) on which it rests has the same chalky appearance. 

 On the other hand, the fragment described on p. 164 xmder the heading M. Mrsuta looks as if 

 it might possibly be the same coral only not corroded (cf. remarks there made). 



The peculiar featui'e of the type is the formation of the thin keels along the ridges of 

 the swollen interstices. These are most marked on the upright processes, due to continued 

 budding from the walls of the ramparted calicles. This same method of formation of 

 processes takes place in M. caliculata. 



a. Tonga (with M. alcicornis). J. J. Lister, Esq.* 91. 3. 6. 28. (Type.) 



43. Montipora irregularis. 

 Moniipo^-a irregulark, Quelch, Chal. Eep., Eeef Corals (1SS6) p. 173, pi. viii. figs. 4, 4a. 



Description. — Corallum a loosely branching mass with irregular encrustiag base, the edges 

 of which creep downwards, covering the former growth, and are rarely free ; the cylindrical 

 or slightly flattened branches twist and curl out of the perpendicular, fusing to form arches 

 and other irregular shapes ; the growing tips are mostly thin and sharply or bluntly tapering. 

 The branched processes rise 10 to 12 cm. above the encrusting base. 



The calicles are conspicuous, crowded, largest (1 mm.) on the encrusting base and thick 

 branches, but less on the thinner processes and taperiag points, generally less than their 

 diameter apart. The margia is often a narrow, smooth, flat, white rim lying in the base of the 

 rampart, and from the edge of which the septa project like echinulas, often sloping upwards. 



* This specimen was purchased by Mr. Lister in Tonga, and no information can now be obtained 

 as to its exact locality or condition when collected. 



