1897] SOME NEW BOOKS 125 
to the modifications introduced by Martin Duncan and Quelch will 
scarcely recognise the classification set forth in a very ingenious 
diagram on page 331 of this work. Corals are divided into two 
sections, Zaphrentoidea or Madreporaria Haplophracta and Cyatho- 
phyloidea or Madreporaria Pollaplophracta. The former section is 
divided into two sub-sections, the Coenenchymata, including the 
families Poritidae, Madreporidae, Pocilloporidae, Oculinidae ; and the 
Murocorallia, including the Zaphrentidae, Turbinolidae, Amphias- 
traeidae and Stylinidae, the two last named being new families, or 
nearly so. Huphyllia is taken as the living type of the Amphias- 
traeidae, Galaxea of the Stylinidae. The section Pollaplophracta is 
divided into two sub-sections ; the Septocorallia, including the families 
Cyathophyllidae, Astraeidae and Fungidae, and the Spinocorallia, 
including the family Eupsammidae. It will be seen that the old 
groups of Aporosa and Perforata as well as the Rugosa disappear 
altogether ; that corals which were known as perforate are placed . 
alongside of aporose corals and vice versé ; thus the Eupsammidae 
are ranked near the Astraeidae, the Pocilloporidae near the Madre- 
poridae. 
These sweeping changes are based upon a microscopic examina- 
tion of the coralla of many recent and extinct forms. Make a section 
through a coral skeleton and you will recognise in the middle of each 
septum, or other component, a dark line or centre. With thin sections 
and high powers the dark line resolves itself into a series of dark 
spots, from which the crystalline elements of the corallum radiate 
outwards in diverse ways. A close comparative study of these features 
has convinced Miss Ogilvie—or we should rather say now, Mrs 
Gordon—that they afford a new and natural basis for classification, 
one which is applicable to the study of both extinct and recent corals, 
because the feature in question is usually well preserved in fossil 
remains. A further convenience is the fact that the microscopical 
structure of the corallum may often, if not always, be inferred from 
its superficial characters, e.g. granules, striae, and serrations of septa. 
To give details of the septal characters is here impossible ; the struc- 
ture is intricate and demands much space for explanation. It need 
only be said that anybody, having read this part of the work, may 
easily verify the truth of the statements made. Points which have 
hitherto escaped notice are here brought forward for the first time, 
and the new observations are invested with an importance which, if 
not always acceptable, is invariably interesting and suggestive. 
Miss Ogilvie not only describes the microscopic character of the- 
corallum; she also accounts for it by seeking to prove that the 
ultimate elements of the coral skeleton are minute scales, each com- 
posed of a bunch of minute crystalline fibres, and that each such scale 
is in fact a calcified cell or calicoblast, which is bodily converted into 
the calcareous tissue of the skeleton. In making this assertion Miss 
Ogilvie treads on contentious ground. She adopts and expands a 
view originally put forward by von Heider, but not generally accepted, 
because it appeared to be negatived both by examination of fresh adult 
coralla and by the embryological researches of von Koch. The latter 
author, whose statements are worthy of the utmost credit, states most 
positively that in the development of <Astrozdes calycularis, the first 
