2 2 THE GENUS MONTICULIPORA. 



clearly dimorphic, and therefore possesses a " coenenchyma," in 

 the sense in which Dybowski uses this term. The D. Hay- 

 denii, Dyb., seems to belong to that section of the Monticuli- 

 poroids to which I have given the name of Monotrypa. Lastly, 

 the Dianulites sidcatus, Dyb,, differs radically from all the pre- 

 ceding forms in the fact that it possesses perforated tahdce in 

 the large corallites ; and it either belongs to Prasopora, Nich. 

 and Eth. jun., as subsequently defined, or it is nearly allied 

 to this. 



Upon the whole, therefore, I find it impossible to accept 

 Dianulites, Eichw., as emended by Dybowski, as being a 

 natural group, and I cannot agree with the suggestion made 

 by Dr Steinmann (N. Jahrb. flir Min., 1880, p. 438) that this 

 division ought to supplant Diplotrypa, Nich., or that it is in 

 any way the equivalent of the latter. 



The genus Soieiiopora, Dyb,, is defined as including forms 

 with an irregular spheroidal corallum. The corallites are pris- 

 matic, and of very small diameter ; there is no " coenenchyma," 

 and tabulae are wanting. The single species described under 

 this head — viz., 6". spongioidcs {loc. cit., p. 124, PI. II. figs. i\a, 

 I lb) — is said to have a smooth and shining surface, and to show 

 no obvious calicine apertures. It seems tolerably certain that 

 this form can have no relationship with the Monticuliporoids, 

 though it is difficult to say anything positive as to its real 

 affinities. I should rather be disposed to suggest that it may 

 prove, on further examination, to be related to the singular 

 type described by Mr R. Etheridge, jun., and myself under 

 the name of Tctradiicm Pcachii (Ann. Nat. Hist. 1877, and 

 Mon. Sil. Foss. Girvan, vol. i, p. 31, PI. I. fig. 3, and PL II. 

 figs. \-\b). 



The third genus of Monticuliporoids in Dr Dybowski's 

 arrangement is Callopora, Hall. It is unnecessary to discuss 

 the characters ascribed by Dybowski to this genus, as the 

 forms included under it are of quite different affinities, and as, 

 moreover, there is at present no sufficient reason to doubt that 

 Callopora, Hall, is a synonym oi Fistulipora, M'Coy, the latter 



