2C)6 TABULATE CORALS. 



Monticulipora (Heterotrypa) ramosa, Edwards and Haime. 



(PI. XIII., figs. 2, 2 a.) 



Monticulipora ramosa, D'Orbigny, Prodr. de Pal(^ont., t. i. p. 25, 1850. 

 Chtztdes ratnosus, Edwards and Haime, Pol. Foss. des Terr. Pal., p. 266, 



PI. XIX., figs. 2, 2 a, 1851. 

 MonticuIipoi-a ramosa, Edwards and Haime, Brit. Foss. Cor., p. 265, 1854. 

 Chatties Dalei, Nicholson, Quart. Journ. Geol. Soc, vol. xxx. p. 501, PI. 



XXIX., figs. 1, I a, 1874; Pal. of Ohio, vol. li. p. 192, PI. XXL, figs. 



I, I a, 1875. 

 Chaietes ramosus, Nicholson, Ann. Nat. Hist., ser. 4, vol. xviii. p. 88, 1876. 



Spec. Char. — Corallum dendroid, of cylindrical or elliptical 

 branches which divide dichotomously, and vary from one to 

 three or four lines in diameter. Corallites markedly divided into 

 two series, the larger ones being rounded or elliptical, about a 

 seventh or an eighth of a line in their long diameter, and open- 

 ing on the surface by subpolygonal calices, which have some- 

 what thickened margins. The small corallites are excessively 

 numerous, surrounding the larger tubes in a single row, and 

 often completely isolating them, their shape and size being very 

 variable. In internal structure, both sets of corallites are 

 traversed by complete horizontal tabulae, which are much more 

 numerous in the small tubes than in the large ones. Walls 

 thickened towards the mouth. Surface covered with conical or 

 somewhat elongated " mamelons," placed at intervals of from 

 half a line to a line, and not occupied by corallites of specially 

 large or small dimensions. 



Obs. — The external characters of this species are too well 

 known to require further remark here ; but we may note the 

 following features in the intimate structure of the corallum, as 

 shown in thin sections. In thin tangential sections (PI. XIII., 

 fig. 2) the most striking appearance is the conspicuous division 

 of the corallites into two sets of tubes, large and small, and the 

 great development of the latter. The large tubes are very 

 uniform in size, generally oval or circular in shape, and mode- 

 rately thick-walled ; the thickening of the wall, however, never 



