562 PROF. P. MARTIN DUNCAN ON MICRABACIA CORONULA. 
Lately, during a revision of the genera of the Corals, I have care- 
fully re-examined the structure of Micrabacia coronula, and have 
compared its internal morphology with that of Fungia and Anabacia, 
and especially with that of a new recent species (Diafungia granu- 
lata, nobis *), which, although it cannot enter the genus Micra- 
bacia, presents in many points very striking resemblances. . 
Micrabacia is one of those genera the comprehension of which is 
impossible without the study of the nearest allied recent genus. 
This modern type is the genus fungia (pars Lamarck, consolidated 
by Dana). The nature of the synapticula of Fungia (the essential 
morphological element of the family in which the genus is placed), 
the character of the septa (some solid, some perforate), and the 
nature of the wall, hitherto quite misunderstood, were considered 
in a communication to the Linnean Society f. 
On comparing Micrabacia with other members of the subfamily 
Fungine, it is evident to me that MM. Milne-Edwards and Jules 
Haime were perfectly correct in their estimate of the classificatory 
position of the genus—that it is allied to the genus Fungia, and that 
it has been misplaced by M. de Fromentel. 
The following is the generic diagnosis given by Milne-Edwards 
and Jules Haime in ‘ Hist. Nat. des Corail.’ vol. 11. p. 29, 1860 :— 
“The corallum is simple, lenticular, plano-convex, and without 
trace of adherence. The wall is sensibiy horizontal: it presents 
delicate non-echinulated and simply granular coste, which alternate 
with the outer edge or margin of the septa, and the intercostal 
grooves have a regular series of little perforations. The septa are 
moderately numerous, straight, denticulated, and are free at their 
inner edge. The columella is rudimentary or does not exist.” 
Milne-Edwards and Jules Haime distinguish Micrabacca from 
Fungia because the first-named has non-echinulated coste, and the 
last has its septa and coste directly continuous. These authors do 
not describe the synapticula of Micrabacia, nor the method of forma- 
tion of what they call the wall, which is regularly perforated. 
These are important points, and it is necessary to study them, 
and also the condition of the septa, which are said by one author to 
be perforated. 
This research is all the easier since the description of the genus 
Fungiat explained the nature of the synapticula, their relation to 
a system of interseptal channels opening at the base of the coral, 
and communicating with the medium at the surface of the calice also, 
and the structure of the base itself, which has not a true theca or 
wall. 
In manipulating Wicrabacia, sections should not be cut vertically, 
but the coral should be fractured with bone nippers in that direc- 
tion. The result is to show the synapticula well. 
Taking the structural details given by MM. Milne-Edwards and 
Jules Haime, in the order followed by those authors, there is no doubt 
that the shape of the corallum is what they state it to be. But the 
* Journ. Linn. Soc. Zool, vol. xvii. p. 417. t Ibid. p. 137. t Ibid. 
