TRIBE I. ASTR^EACEA. 267 



The Monticularise are Meandrinae in which the polyps are confluent 

 across the ridges, in consequence of which, the ridges are reduced to 

 mere conical prominences, consisting of lamella? radiating more or less 

 regularly from the centre. The polyp mouths are situated in the in- 

 tervals between the prominences, as is shown in plate 13, figure 13 b, 

 and around these prominences the tentacles are clustered. The spe- 

 cies form convex masses, either subglobose, incrusting, or gibbous, 

 the last rising into knobs or rudimentary branches ; and the texture 

 within is cellular throughout. There are some explanate and branch- 

 ing corals which have the surface-cones of the Monticulariae, but the 

 internal solid texture of the MerulincE, into which they graduate, and 

 with which they are here arranged. 



These corals are confined, as far as known, to the coral-reef seas, 

 and within twenty fathoms of the surface. 



This genus was instituted by Lamarck, and named in allusion to 

 the little cones or monticles of the surface. The genus Hydnophora, 

 of Fischer (Oryct. de Moscou), includes the same species, and some 

 fossils of doubtful character (partly Agaricioid], which he unites with 

 them. 



Arrangement of the Species. 



I. Convex or subglobose. 

 *1. M. microcona. 



II. Gibbous. 



*2. M. lobata. *3. M. polygonata. 



1. MONTICULARIA MICROCONA. (Lamarck.) 



M. conveza, subhemispherica ; discis cinnerascentibus ; tentaculis nume- 

 rosts, pallide brunneis. Corallum cellulosum ; conulis parvis, fere 

 cequalibus, scepius obsolete compressis ; lamellis subtiliter serrulatis. 



Convex, subhemispherical ; disks ash-coloured, tentacles numerous, 

 pale brown. Corallum cellular; conelets small, nearly equal, usu- 

 ally obsoletely compressed ; lamella? finely serrulate. 



Plate 13, fig. 13 a, enlarged view of the surface of the corallum ; 

 13 b, enlarged view of the live zoophyte ; 13 c, transverse section of 

 corallum, enlarged; 13 d, vertical section, enlarged ; 13 e, polyps in- 



