MEDITEEBANEAN AND NEW-ZEALAND EETEP0E2B. 259 



S. -f essellata groTi]^, they would have to remain in the same family 

 as Ret ep or a. 



The genus Betepora is found fossil throughout the Tertiaries, 

 but does not seem to occur in the Cretaceous period. 



Eetepoea cellulosa, L. (PI. VI. figs. 17 & 20 ; PI. VII. 

 fig. 12.) 



Retepora cellulosa, Smitt, Krit. Fort. of. Skand. Hafs-Bryozoer, iv. 

 1867, pp. 35 and 203, pl. xxviii. figs. 222-225. 



Although so many authors have mentioned B. cellulosa, there 

 does nob seem to be any satisfactory description, most having 

 apparently had two or three forms before them ; and out of the 

 very long list of synonyms usually quoted, I cannot find more 

 than the single one above given which can be relied upon. Such 

 figures as those of Ellis, Lamouroux, and Blainville will do equally 

 well for two or three species ; and no doubt Busk, in his ' Cata- 

 logue of the Marine Polyzoa,' figured more than one. Quotations 

 from such works as Lamarck's * Animaux sans Vertebres,' where 

 for a. reticulata and the other species no single zooecial character 

 is mentioned, only waste time by causing useless references ; and 

 in this special case, though no doubt the figure quoted by Lamarck 

 is that oiFrondipora verrucosa,!^ has been considered as a synonym 

 of R. cellulosa. Eisso describes it as " presque membraneux.'^ 



Out of the Mediterranean species there is one which we must 

 now consider as the type, without being at all sure that this is 

 the one which was in the hands of those who first gave the name. 

 It is not a stout species, and I have not often seen it grow to any 

 considerable size, but usually the colony is cup-shaped. The 

 peristome is but little raised, with a spine at each corner ; it has 

 a distinct sublabial pore, which, however, seems to have been 

 mistaken for an avicularium by some authorities, including 

 apparently Busk in his ' Crag Polyzoa.' The operculum becomes 

 much wider at the proximal border. 



There is no avicularium within the peristome, and in this respect 

 it differs from B. atlantica, Busk, and B. mediterranea, Smitt ; 

 but there are numerous small avicularia scattered over both the 

 front and dorsal surface ; a few large erect avicularia occur with 

 the opening directed to the distal end of the zooecium. 



The ovicell has a fissure in the calcareous wall, which of course is 

 covered by an integument, and is identical in structure with those 

 of B. Beaniana, B. atlantica, B. mediterranea, B.Jissa. The front 



