2 4 THE GENUS MONTICULIPORA. 



to say that there seems no reason to doubt the correctness of 

 their reference to Constellaria. 



The sixth genus is Orbipora, Eichw. (emend, Dybowski), 

 which is defined as comprising forms with a polymorphic cor- 

 allum, composed of tubular corallites, the thickened and lam- 

 ellar walls of which are amalgamated with one another. Scler- 

 enchymatous structures of a string-like character (" Wand- 

 strange") are developed in the walls of the corallites; and 

 there may or may not be tabulae. The forms referred to it 

 are O. distincta^ Eichw., O. fungiformis, Eichw. (this last not 

 described), O. arborescejis, Dyb., and O. Paiidcri, Dyb. I 

 have already given a brief account of Orbipora, Eichw. (p. 1 1), 

 and need only add that the definition of the genus given by 

 Dybowski, as indeed he himself admits, is in all essential points 

 an entirely different one to that of its original author. I have 

 also, already, in speaking of Dianulites, Eichw. (pp. ii, 12), 

 given the reasons which render me, in liuiine, entirely opposed 

 to all attempts to revive old generic names which were, to be- 

 gin with, unrecognisably characterised ; and I consider these 

 reasons to be just as powerful in this particular case as in the 

 instance of Dianulites. I need only add, therefore, a few re- 

 marks upon the species which Dybowski refers to Orbipora 

 Eichw., so far as I have been able to study these without 

 actual specimens. O. distincta, Eichw. {loc. cit., PI. II. figs. 

 \oa, lob), is apparently a Monticuliporoid, with numerous abor- 

 ted spiniform corallites (" Wandstrange "), greatly thickened 

 walls, and no tabular. I am not acquainted with any form 

 which very closely resembles this. O. arborescens, Dyb. (PI. 

 II. figs. 8^:2;, 8^), is a Monticuliporoid which is very closely 

 allied to M. hunida, Phill, of the Carboniferous rocks. On 

 the other hand, O. Pandcri, Dyb., seems to be a true Steiio- 

 pora, Lonsd., nearly allied to S. crinita, Lonsd. (of which I 

 have examined typical specimens by means of thin sections), 

 and, like it, not a normal type of the genus. The spine-like 

 processes (" dornformige Vorsprlinge ") which Dybowski de- 

 scribes and fiofures as seen in lonof sections of the corallites, 



