XXVlll 
IXTRODUCTIOX. 
The majority of his families of Cyclostomata are also natural, 
though they require amendment in accordance with fifty -six 
years further knowledge. In spite, however, of the large amount 
of truth in the classification, it has not been widely adopted. Its 
neglect has probably been largely due to the fact that it was 
unnecessarily complex for those who had to deal with the com- 
paratively few Cyclostomata of existing seas. The members of 
that fauna can be referred to a few widely separated families, 
and suborders are of little practical convenience. 
Von Hagenow, unfortunately for his work, was unable to use 
d’Orbigny’s classification, since be published his monograph on 
the Bryozoa of the Maastricht Limestone in 1851, and before 
d’Orbigny’s revised classification had been issued. Yon Hagenow 
divided the fossil Bryozoa into four groups, the names and 
approximate equivalents of which are given in the following 
table. Unfortunately he made no attempt to divide his groups 
into families. 
Tubuliporina = the Cyclostomata Tubulata. 
Cerioporina = the Trepostomata and Cancellata. 
Salpingina (for the two genera Eacliarites and Inver saria) = 
Eleidse. 
Hrceolata = Cheilostomata. 
The next important contribution was by Busk in his “Mono- 
graph of the Fossil Polyzoa of the Crag” (London, 1859). This 
Pliocene fauna included seventeen genera of Cyclostomata, which 
he distributed among six families ; but in an important synoptical 
arrangement of the Cyclostomata {op, cit. p. 91) he included thirty 
genera, which were apparently all that he admitted, in*^ spite of 
d’Orbigny, as valid. He remarked that for this Order ‘ ‘ our principal 
reliance in the distinction of genera and species must be placed 
on the general form of the polyzoary [zoarium], and the mutual 
relations of the cells.” He ignored important structural differences 
in the zooecia, and his six families of Inarticulate Cyclostomata 
are therefore mostly artificial groups. Thus he placed Eiastopora 
in a different family from Alecto {Stomatopora) and Mesenteripora, 
and in the same family as Patinella, Discoporella, and Defrancia. 
Busk must have modified his views while the monograph was in 
course of publication, for in the table on p. 91 he placed Alveolaria 
in the Cerioporidae, but in the text he included it in the Theonoidae. 
