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THE BRITISH CARBONIFEROUS TREPOSTOMATA. 
I.—Introduction. 
A cursory review of the more salient points in the history of research among the 
Trepostomata will show that there is urgent need that the British representatives of this 
widespread sub-order should be classified, and as far as possible described, so as to permit 
of their being made use of by investigators. 
Abundant as the Trepostomata are now known to be in the Palaeozoic deposits of 
various regions, the investigation of their nature depends on the use of the microscope ; 
and as the older authors necessarily based their determinations on external features only, 
it is not surprising that but few species were recognised until the middle of the second 
half of the last century. Previous to that time the ramose mode of growth was thought 
to be the principal characteristic of the group, which was generally referred to the 
Tabulate Corals and restricted to a very limited number of species, credited with a long 
vertical range and wide horizontal distribution. No systematic work was attempted, and 
new names—in the West of Europe at least—became speedily buried in synonymic lists. 
M‘Coy, who was in so many ways in advance of his contemporaries, suspected the 
importance of the group, without, however, proposing a classification. 1 
In 1866 a bold step was taken by C. Rominger in advocating the removal to the 
Bryozoa of several forms allied to “ Chaetetes ,” 2 and similar conclusions were expressed by 
Lindstrom in 1873. 3 
In the year 1877 appeared Dybowski’s memoir on the Chsetetids of the East-Baltic 
Silurian, and two years later Nicholson’s monograph of the Tabulate Corals. These two 
works—especially the latter—mark a new era in this branch of research, showing the 
absolute need of thin sections and careful microscopical examination. The importance 
of the impetus they gave to subsequent study can hardly be overestimated. 4 Regarding 
the systematic position of the Monticuliporids, no definite conclusions were reached by 
Dybowski, but Nicholson maintained that their affinities are with the Tabulate Corals, 
which view he continued to hold in his later works. 
In the classification adopted by von Zittel in the original edition of his “ Handbuch 
der Palaeontologie,” published from 1876 to 1880, the Monticuliporids form with Chaetetes 
1 21, p. 193. 2 35a. 3 17a. 4 5 a ; 25. 
(22239—17.) Wt. 26725—59. 301. 5/12. D. & S. A 2 
