46 J. E. DUERDEN. 



teries bearing the sexual products of the polyp. This was first 

 suggested by Moseley (Q. J. M. S., XXII., p. 394), from his 

 studies of the living coral Scriatopora, in the following words : 

 "The presence of the deep pits in Seriatopora for the reception 

 of the single pair of generative mesenteries and their hypertrophied 

 mesenteries may possibly explain the pits occurring amongst the 

 septa of some palaeozoic corals which may have had a similar 

 function." 



This theory has met with general acceptance only among 

 English writers, particularly Nicholson, Ogilvie, and Bernard. 

 It is founded entirely upon conditions met with in the modern 

 Seriatopora. In the polyps of this genus, only the six primary 

 pairs of mesenteries are present, the first developmental pair being 

 by far the largest and bearing the gonads. In other corals, e..g., 

 Pocillopora, Forties, and Acropora (Madrepord), a like inequality, 

 though to a less degree, is met with wherever only the six pri- 

 mary mesenteries occur, but as further cycles of mesenteries 

 appear the six primary pairs become equal and are all fertile ; 

 moreover, in zoantharian larvre the first pair of mesenteries often 

 greatly exceed the others in the extent of their development. 

 As regards their mesenteries the adult polyps of Scriatopora 

 are merely at an early phylogenetic stage, and the skeletal pits 

 are correlated with this. Our knowledge of the Anthozoa as a 

 whole gives no support whatever for thinking that any of the 

 mature rugose polyps had only two or even only a few repro- 

 ductive mesenteries. Rather, the large number of principal or 

 first cycle septa occurring in rugose corals, all more or less equal, 

 gives good reason for assuming that a correspondingly large num- 

 ber of mesenteries would be fertile, as in the polyps of recent 

 Zoantheae, and also that such fertile mesenteries would be dis- 

 tributed all round the polyp. Moreover, Moseley's suggestion 

 would explain only the occurrence of the pair of deep pits, one 

 on each side of the primary septum ; it would not account for 

 the smallness of the axial septum itself. 



Bernard 1 (1904, p. 10), while accepting that the use assigned 



1 Bernard, H. M., " The Prototheca of the Madreporaria, with Special Reference 

 to the Genera Calostylis, Linds., and Moseleya, Quelch," Ann. Mag. Nat. Hist., 

 Ser. 7, Vol. XIII., Jan., 1904. 



