BRITISH PAL^OGENE BEYOZOA. 221 



Peristomial Pore (" Sublabial pore " of Busk) . A pore below the aperture which simply leads into 

 the peristomial chamber. 



Punctitres. A series of pores left between the anastomosing spines of the front wall of Cribrilina, &c. 



Areolce. Pits or tubular depressions occurring in linear series ai'ound the margins of zocecia, e. g. 

 in Notmnia luetherellL 



Macula. A term suggested for the small irregular cavities iu the walls of the zooecia : they 

 correspond to the main part of the "pores d'origelles " of Jullien [No. 3, p. 607], but since 

 Pergens [No. 7] has thrown such discredit on Jullien's views on these structures it seems 

 hardly advisable to circulate this term. The name is derived from " maculse/' the meshes of 

 a net, as, according to Pergens, they originate simply by non-calcification of part of the 

 wall. When seen on the fi-out wall of a zooecium they resemble small pits or depressions. 



OpesiuUe. A term applied by Jullien to the secondary small apertures, of which a pair usually 

 occur on the front walls of the zooecia of Micropora, &c. 



III. Classification. 



Probably no one who has tried to determine to which of the twenty to thirty families 

 of Cheilostomata some form new to him must be referred will complain of an attempt to 

 arrange these families into groups. Among the Euechinoidea, for example, there are 

 twenty-five families distributed amongst five orders, some of which are divided into sub- 

 orders. But among the Cheilostomata we have as many or more families, without any 

 definite larger groups, except the ill-fated ones proposed by ])r. Jullien [No. 4] and the 

 antiquated ones of Mr. Busk 1. The inconveniences of this are manifold ; the diagnosis 

 of each family has to be of inconvenient length, and the task of discovering the exact 

 systematic position of any species is a matter of much difficulty. 



Neither the Rev. T. H. Hincks nor Mr. Waters off'er much encouragement to an 

 attempt at any serious alteration, as the former points out emphatically that all classifi- 

 cations at present must be tentative and the latter discourages what he calls " an attack 

 along the whole line." But then all classifications are probably more or less tentative 

 and temporary, and, so far as I am able to judge, some grouping of the families is an 

 essential preliminary to an attempt to revise the families in detail and dissipate the chaos 

 in which at present the fossil Bryozoa are involved. 



Though there is of course much uncertainty as to the exact taxonomic value of 

 several characters, there does seem to be a pretty general agreement as to the most 

 important structures. The development of the front wall seems about the leading 

 feature, as so many of the other characters, e. Cj. the aperture, the position and deve- 

 lopment of avicularia, &c., are correlated with this. The use made by Jullien of the 

 front wall has perhaps prejudiced some workers against this structure ; but Jullien has 

 based his classification on modific£i,tions that most workers regard as of very slight value, 

 while his method of nomenclature is quite his own. As M. DoUfus has pointed out in 

 an admirable criticism, Dr. Jullien simply does not accept the principle of priority. 



^ Busk of course based his divisions on zoarial characters, and these, though somewhat improved b\ 

 Dr. Ortmann [No. i, pp. 3, 4], are now quite inadequate. 



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