222 THE GENUS MONTICULIPORA. 



subjected to microscopical examination, and to apply to the 

 present species the name of M. decipiens. Rominger ; since it 

 was certainly this form which Dr Rominger described under 

 the above title. My only reason for not following this course, 

 and for retaining the name of J\L frondosa for the form now 

 under consideration, is that my specimens of this present such 

 a close resemblance to the figures oi M. frondosa, D'Orb., given 

 by Edwards and Haime, that I can hardly believe that they are 

 not in reality identical. It is true that Milne-Edwards and 

 Haime distinctly state that the monticules in the form which 

 they call ]\L frondosa are occupied by corallites larger than the 

 average, whereas in the present form they are made up of 

 corallites smaller than the normal. But the figures given in the 

 " Polypiers fossiles " do not show this alleged feature, and I 

 am not acquainted with any frondescent species of Monticuli- 

 pora from the Cincinnati Group of which it can be truly said 

 that the corallites of the monticules are larger than the average 

 size, to any extent, at any rate, at all comparable with the 

 difference stated to exist by Edwards and Haime. We must 

 either believe, therefore, that this observation of the writers 

 just mentioned was founded on a misapprehension, or we must 

 suppose that their M. frondosa has not been subsequently re- 

 cognised by any who have examined the Monticnliporce of the 

 Cincinnati formation. 



Upon the whole, therefore, and with the above-mentioned 

 reservations, I prefer in the meanwhile to retain for the present 

 species the name of J/, frondosa, D'Orb. At the same time, 

 I fully recognise the worthlessness of D'Orbigny's original 

 definition for purposes of identification, and the impossibility 

 of entirely reconciling the description given by Milne-Edwards 

 and Haime with the characters either of this or of any other 

 frondescent species of the genus with which I am acquainted, 

 I also fully recognise that the M. decipicns of Rominger is un- 

 doubtedly identical with the form now under consideration. 

 That this is the case will be sufficiently evident from an exam- 

 ination of the annexed sections (fig. 47) of a typical example 



