XXXIV 
INTRODUCTION. 
the same year he remarked^ that “the mode of growth in other 
divisions has been clearly shown to have secondary importance, 
and the same thing may to a certain extent be seen here.” 
If Mr. Waters had developed this line of classification, his two 
divisions would probably have been accepted and have proved of 
material service. But he almost at once changed ground, and later 
on the same year based his two divisions on different and inconsistent 
characters. Thus he says, “In the Quart. Journ. Geol. Soc. 
vol. xliii. p. 337, I proposed to divide the Cyclostomata into 
Parallelata, in which there are no cancelli, and Rectangulata, in 
which the openings of the cancelli occur between the zooecial 
tubes.” This basis for the two divisions was published in October, 
1887,’^ and may therefore be regarded as intended to replace his 
original proposal of August in the same year. The use of cancelli 
as the essential character of his subdivisions was inconsistent with 
a classification according to the grouping of the zooecia. Cancelli 
are not present in all rectangulate Cyclostomata, and they are not 
absent from all those with a parallel growth. Hence the name 
Rectangulata is unsuitable to the group with the modified 
definition. 
Ulrich, however, in 1890, founded the Trepostomata, based on 
practically the same principle as that adopted by Hamm and by 
Waters in August, 1887 ; and as there is no uncertainty as to the 
meaning of Trepostomata, and Ulrich used both the zoarial arrange- 
ment and the zooecial modification consequent on it, his name was 
followed in the two previous volumes of the catalogues of the 
Mesozoic Bryozoa. 
As a last example of the successive classifications of the Cyclo- 
stomata may be quoted Ulrich’s of 1900.® 
Crisiidge ... Grisia. 
Diastoporidee ... Stomatopora, Berenicea, Biscosparsa, Biastopora^ and 
Bidiastopora, with the Palseozoic genera Biastoporina, 
Hederella, Smtodia, and Reptaria. 
Idmoneidse ... Idmonea, Bisidmonea, Filisparsa, Filicavea, Filicrisina, 
Flornera, Reticulipora, Retecava, Bierisina, Siilcocava, 
and the Ordovician Protocrisina. 
^ A. W. Waters. “ Bryozoa from New South Wales, North Australia, etc.,” 
pt. hi : Ann. Mag. Nat. Hist. 1887, ser. 5, vol. xx. p. 253. 
Fbid. 
2 In Zittel-Eastman. Textbook of Palaeontology, 1900, vol. i. pp. 260-71. 
