160 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
and also said that the avicularian mandible usually had a short median 
columella, but that it was absent from C. sardonica, Waters, and that this 
structure seemed to be confined to species from the southern hemisphere. As 
I have since shown, C. sardonica has two kinds of avicularia, one of which has 
a columella, and it is curious how in other species the columella occurs for the 
most part in one of the two but not in both; however, it is perhaps more 
frequent in the vicarious avicularia than in the oral. There area large number 
of species in the north and south tropics, in fact the holostomatous forms 
are much more largely represented in the tropics than the schizostomatous 
Cellepora. 
In 1888 MacGillivray *, speaking of the Cellepora as forming two groups— 
the Holostomata t and Schizostomata—separated Schismopora from Cellepora; 
but, as I have already indicated elsewhere, this was unfortunate, as all the 
species which we have long known as Cellepora, including what we may call 
the types, were thereby removed from Cellepora, and this new division, the 
Holostomata, remained under Cellepora. 
It will be recognised from my description that what I propose to call 
Holoporella has various characters by which it is very distinctly separated 
from Cellepora; and already from the old Cellepora a number of species have 
been removed to Lagenipora and Palmicellaria, and others fall into Osthimosia, 
Jull., or Schismopora, MacG. 
In these Red Sea collections there is one Lagenipora, but otherwise the 
Schizostomata group of the old Cellepora is unrepresented, which is strange 
considering how numerous they are in the Mediterranean, though we may 
still expect various species to be found in the Red Sea. 
Where the mandible has a columella, then the lucida always seems placed 
higher up than when there is no columella. 
Although the minute avicularia alluded to have not been mentioned 
previously, yet in various stages of development and frequency they occur in 
C. albirostris, Smitt ; C.apiculata, Busk; C. fusca, Busk ; C. hastigera, Busk ; 
C. honolulensis, Busk; C. aspera, Busk ; C. jacksoniensis, Busk; C. triden- 
ticulata, Busk. We must be alive to the possibility of some of these being 
synonyms. 
One species of Holoporella was, in a paper by Hincks, placed under both 
Monoporella albicans, Hincks, and Schizoporella aperta, Hincks, and is still 
quoted under these two names, although Hincks{ in a subsequent paper 
recognised their identity. An examination of the opercula would at once 
have shown that in spite of a different appearance of the specimens the 
* Prod. Zool. Vict. dec. xvii. p. 241 (1888). 
+ Ortmann in 1890, ‘ Japanische Bry.’ pp. 15, 16, makes the subfamily Holostomata for 
Lepraha, Smittia, &c., and Schizostomata for Schizoporella, &e. 
t Ann. Mag. Nat. ne ser. 6, vol. ix. (1893) p. 176. 
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