lyo THE GENUS MONTICULIEORA. 



irypa, since the type of this section is not M. Mliitcri, but 1\[. 

 iimhtlata, Nich. In the meanwhile, therefore, I must retain 

 this section ; and the following' descriptions of species belonging 

 to it will serve to elucidate its characters more fully. 



Monticulipora (Monotrypa) undulata, Nich. 



(Figs. 32 and 2>z.) 



Chaidcs itiidulatiis, Nicholson, Geol. Mag. Dec. ii., vol. ii. p. 176, 1S75. 

 ,, i//idi//ati/s, Nicholson, Rep. on the Pal. of Ontario, 1875, PP- 1°? 33; 

 PI. IV. fig. I. 

 j\[oitticiilipora [Monotrypa) midiilata, Nicholson, Pal. Tabulate Corals, p. 

 321, PI. XIV. figs. 3 and 4, 1 87 9. 



Spec. Char.- — Corallum forming large, lobed or laterally in- 

 dented masses ; or occurring as smaller hemispherical or spher- 

 oidal masses, of from half an inch to more than an inch 

 in diameter, Corallites uniformly thin-walled, angular, and 

 prismatic in shape, sub-equal in size, the average tubes vary- 

 ing from one-fifth or one-sixth of a line up to a quarter of a 

 line or rather more. The bulk of the corallum is made up of 

 corallites of the smaller of the above dimensions, while the 

 slightly larger tubes form clusters of six or more, which appear 

 on the surface as patches or " monticules," which are but 

 faintly or not at all elevated above the general level. Small 

 corallites are also often present at the angles of junction of the 

 larger tubes, but they may be wanting : they are never a con- 

 spicuous feature, and their internal structure is the same as 

 that of the normal corallites, Tabuke horizontal, complete, 

 remote, equally distributed through all the tubes of the colony, 

 and often placed at corresponding levels in contiguous tubes, 

 so that the corallum breaks up Into a series of concentric 

 strata. 



Obs. — The type of this species is a large and massive coral, 

 which occurs In the Trenton Limestone of Canada. With this 

 I formerly associated certain large and lobate IlIoiitictLlipoi^cE 

 from the Cincinnati Group of Ohio and the Hudson River for- 



