2i6 THE GENUS MONTICULIPORA. ' 



the vicinity of the surface, as well as, generally, by the abun- 

 dance of their spiniform corallites. 



I propose to include under the head of Peronopo7'a the fol- 

 lowing species of Monticnlipora — viz., M. frondosa, D'Orb. 

 { = M. decipieiis, Rom.), AI. Cinciiznatiensis, James, M. violcsta, 

 Nich., and M. ? Orto7ii, Nich., the last being an aberrant and 

 ill-understood form ; and I subjoin descriptions of these as 

 illustrating the structure of this peculiar group. 



Monticulipora (Peronopora) frondosa, D'Orbigny. 



(Figs. 46, 47, and PL V. figs. 4, 4a, and 5, 5<?.) 



Monticulipora frondosa^ D'Orbigny, Prodr. de Pale'ont., vol. i. p. 25, 1850. 

 Chcetetes frondosus, Milne-Edwards and Haime, Pol. Foss. des Terr. Pal., p. 



267, PI. XIX. figs. 5, 5^-, 1851. 

 C/icEfefcs decipiivis, Rominger, Proc. Acad. Nat. Sci. Phil., p. 116, 1866. 

 ChcBides frondosns, Nicholson, Quart. Journ. Geol. Soc, vol. xxx. p. 508, 



PI. XXX. figs. 2-2^, 1874; Pal. Ohio, vol. ii. p. 208, PI. XXII. figs. 



i-ib, 1875 j Ann. Nat. Hist., ser. 4, vol. xviii. p. 91, figs. 11, \\a, 1876. 



Spec. Char. — Corallum composed of erect, flattened, undu- 

 lating expansions, of unknown but often considerable height, 

 varying in thickness from less than one line to about four lines. 

 Surface covered at short intervals with numerous rounded or 

 stellate spaces which are often elevated to form low but quite 

 distinct monticules, while at other times they are level with 

 the general surface, and which are occupied, wholly or mainly, 

 by small tubuli, such as separate the ordinary calices. The 

 larger calices are moderately thick- walled, irregularly circular 

 or oval in shape, and about i-iooth inch in diameter on an 

 average. They are surrounded by a variable, but always large, 

 number of smaller irregularly shaped corallites, which occupy 

 all the intervals between the preceding, and sometimes almost 

 surround them. In addition to these there exist very many 

 minute, circular, thick-walled tubuli ("spiniform corallites"), 

 which appear on the margins of the ordinary calices as very 

 minute circular apertures or as apparendy closed tubercles. 



