General lUstorij of the Marine Polyzoa. 479 



Note on Hiantopora ferox, MacG., and 

 Cribrilina monoceros, Busk. 



In the earlier portion of this paper I have referred to Mr. 

 Kirk Patrick's remarks on the systematic position of the former 

 of the above species, and have sng'gested that there is probably 

 a close affinity between it and CrihriUaa monoceros. A careful 

 examination and comparison of the two forms has convinced me 

 that they are very nearly related and should probably find a place 

 in the same genus. E-everting for a moment to Mr. Kirk- 

 patrick's paper, I venture to suggest that the form which he 

 describes as a variety [inter media) of Memhranipora radi- 

 cifera may prove to be only an early stage in the develjpmeat 

 of Hiantopora ferox. His figure certainly bears a very close 

 resemblance to cells of the latter species on the growing edge 

 of the colony which have lately come under my notice. The 

 zocecium represented in his figure is in an early stage of 

 growth ; the lower margin of the orifice is incomplete, but 

 from the base of the avicularian cell (or from the margin 

 beneath it) processes are budding which, in conjunction 

 probably with offshoots from the side-wall of the cell, have 

 already all but formed one or two of the large pores which 

 are so striking a feature of the species. A marginal cell in a 

 fine colony of H. ferox (which Miss Jelly has kindly lent me 

 for examination) is in a similar stage of development, and 

 presents very much the same appearance. Other cells 

 exhibiting various phases of growth enable us to trace the 

 history of the mature form. 



As to the relationship between this species and G. mono- 

 ceros there can, T think, be little difference of opinion. The 

 development of the zooecium is essentially the same in both. 

 In its earliest stages the cell is simply Membraniporine in 

 character ; the first change is the completion of the calcareous 

 framework of the orifice, which is effected by the formation of 

 a bar across the aperture, which shuts off the upper portion 

 of it and constitutes the inferior margin of the oral opening. 

 By the successive growth of a number of calcareous processes 

 from the lower margin of the orifice and the side-walls of the 

 cell, the extremities of which meet and are fused together, 

 a perforated shield is formed which arches over and protects 

 the membranous front wall. As 1 have said, the method of 

 construction is similar in both forms, and the structural 

 elements are alike. They may certainly rank in the same 

 genus, and probably in MacGiUivray's Hiantopora. 



The affinity between these forms and the CribrilinidEe is 

 sufficiently apparent, but they can hardly be included in tlie 



