8 THE VOYAGE OF H.M.S. CHALLENGER. 
Of a large number of representative genera of Reef-Corals, little or nothing is known 
of the early stages of the growth either of their simple or of their colonial forms ; nor, 
indeed, does it seem likely that such knowledge will be forthcoming, until some naturalist 
familiar with the subject has been enabled to collect and study the various types on the 
reefs. 
In the treatment which has been given of the old group of the Rugosa, I have been 
warned, as indeed I am aware, that I shall probably be subjecting myself to a good 
deal of criticism; but the conclusions at which I have arrived seem to me unavoidable, 
when the essential characteristics of the main groups of the recent and fossil corals are 
compared. Nor would these conclusions be disturbed by the removal of many doubtful 
genera from the Madreporaria: 
The question has been briefly discussed, and was rendered necessary to be discussed 
by the occurrence of the very remarkable form, Moseleya latistellata, the direct and close 
relationship of which to the most typical of the Cyathophyllide is self-evident, while at 
the same time it is also undeniably Astreeid in its characters. 
I was inclined at first to place the Cyathophyllide, together with Moseleya, definitely 
in the family Astraeidze as a subfamily Moseleyinee; but it seems more advisable to 
consider the two families as distinct, Moseleya being placed with the Cyathophyllide. 
It is evident, however, that the essential distinctions between the two families are very 
slight. 
Considering the extremely interesting relationships of Moseleya, it must be looked 
upon as one of the most remarkable types of structure brought to light by the Challenger. 
ON THE LITERATURE. 
It has not been thought necessary to give in this short work a list of the bibliography 
of the Reef-Corals, for while numerous works exist in which lists are given of the older 
works on the subject, full information of the more recent works has been given in the 
recently published and valuable volume by Professor D’Arey Thompson, A Bibliography 
of Protozoa, Sponges, Coelenterata, and Worms. 
Constant reference has necessarily been made for the recent forms to the works of 
Dana, Milne-Edwards and Haime, Verrill, Pourtalés, Agassiz, Duchassaing and Michelotti, 
Duncan, Semper, Moseley, Lacaze-Duthiers, Lindstrém, Briiggemann, Studer, Klunzinger, 
Ridley, Tenison-Woods, &c., not to mention the older writers; and references to writings 
of the different authors are given in the systematic portion of the work under the genera 
and species, . 
