﻿42 MADREPORARIA. 



2-i. Montipora compressa. (PI. III. fig. 5 ; PI. XXXI. fig. 20.); 



Millcpora compressa, Esper (non Linnasus), Pflanzenthiere, i. (1791) p. 203, taf..x. 

 Maiwpora compressa, Dana, Zooph. (1848) p. 49i. 



Montipora compressa, Milne-Edwards and Haime, Ann. d. Sci. Nat., (3°) xvi. (1851);p. 63; 

 Montipora rigida, Q,ne\ch..{mm Verrill); Chall. Rep., Reef Corals (1S86) p. 173. 



Description. — Corallum a loose, bush-like cluster of long and very irregular branches, often' 

 broadened and flattened, fragments often resembling young reindeer horns, with the branchlets 

 short and thick. The thinner cylindrical portions of the main branches are about 1 cm. 

 thick. Branches fuse freely. Height at least 16 cm. 



Calicles conspicuous, neatly circular, about 0'75 mm. in diameter, averaging about 1 mm. 

 apart, each calicle lined by a memljranous layer of coenenchyma which rises slightly above 

 the surface as a thin white ring. On the young branchlets and growing tips, the proximal 

 edges of this membranous wall stand out so that the calicle looks slightly upwards ; elsewhere 

 the ring lies parallel with the interstice. Septa, as a rule, very irregular and feeble at the 

 margin, but become more prominent deep down in the fossa. Occasionally the white ring is 

 regularly and evenly bent so as to follow the^ outlines of six equal, short, petaloid, interseptal 

 loculi (cf Esper's fig. 3 and PI. XXXI. fig. 20, left lower corner). 



Ccenenchyma shows in section a thick, strong,. laminate streaming; layer, sharply marked 

 off from a radial layer which is often so^ dense as to appear solid, with the exception of the 

 irregular canals andi pores running through it. The basal fragments are much hea\der than 

 the younger fragments from the upper portions of the stock. The interstices are covered by 

 conspicuous white Lines and granules, often, grouped to form a flat network joining the white 

 rings round the calicles. Tlus network is,, however, seldom so conspicuous as are the calicular 

 margins.. 



There are teni fragments of tiiis coral which can be fitted together to form two specimens, 

 one of which («) is a^ large and. imposing stock, 16 cm. in height (figured on PI. III. fig. 5). 

 This species is distinguished from the next chiefly by the greater coarseness of the surface 

 texture and the larger size of its calicles. 



Quelch's identification of this with VerriU's ill. rigida cannot stand, as there is no trace 

 of the foveolation. which appears to be the special characteristic of Verrill's type. On the 

 other hand, the peculiar and slightly prominent white membranous rings lining the apertures 

 of the calicles ally, it unmistakably with the M. compressa figured by Esper. This author had 

 identified his specimens, which were from some unknown locality, with the Millepora compressa 

 of Linnseus,* said to be from the Mediterranean, a locality which practically excludes the 

 possibility of this identification. Dana first recognised that Esper's type was a true 

 Manopore (Montipore). 



In addition to the peculiarity which characterises the type, it is- worth, noting, that, the 



* Syst. Nat., ed. xii. (1766) p. 1283. 



