SUB-GENUS PERONOPORA. 221 



the following definition : " Espece a larges frondes dont les 

 monticules sont coniques et tres-espaces." Now it is evident, 

 to begin with, that this definition is absolutely worthless, and 

 might apply to any one of three or four quite different frondes- 

 cent species of Monticulipora. Indeed I know of no frondes- 

 cent form of the genus in which the monticules could, with any 

 special propriety, be described as " tres-espaces ; " so that almost 

 the only positive character mentioned by D'Orbigny is thus 

 rendered useless in the present inquiry. 



Milne-Edwards and Haime, in their great work on the 

 Palaeozoic Corals, figure M. frondosa, D'Orb., and give the 

 following description of its characters : — 



" Polypier en larges frondes, epaisses de quelques millime- 

 tres ; mamelons arrondis, peu saillants, subradies, larges d'un 

 millimetre et demi, et distant d'une fois et demi, rarement 

 deux fois leur largeur, presentant a leur sommet les plus 

 grands calices : ceux-ci ont un tiers de millimetre, et les plus 

 petits un cinquieme." 



It will be observed that in the above description Milne- 

 Edwards and Haime describe the monticules as rounded, 

 somewhat stellate, and slightly prominent, whereas D'Orbigny 

 describes them as conical ; and the distances which they give 

 as separating the monticules (variable as this character always 

 is) would certainly not justify us in applying the term " tres- 

 espaces " to these structures. Now, a perusal of the above 

 definition by Milne - Edwards and Haime will at once show 

 that it is not sufficient for anything like a satisfactory deter- 

 mination of the true characters of 31. frondosa, D'Orb. We 

 do not know that these accurate and painstaking observers 

 actually had D'Orbigny's specimens under their examination ; 

 and, in any case, their description, as was inevitable at the 

 time it was written, embraces purely external characters, and 

 is therefore necessarily vague and unsatisfactory. 



Under these circumstances, the really wisest plan, perhaps, 

 would be to abandon the name o{ HI. frondosa altogether in 

 the meanwhile, until D'Orbigny's original specimens can be 



