IO MARINE BIOLOGY OF THE SUDANESE RED SEA. 
Although Savigny did not figure the small round avicularia, he otherwise 
gave a fair figure showing the ovicell, so that the species is recognisable. 
Nevertheless it has not been easy to decide which of the two names should 
be retained. 
Loc. Lifu (Ph.) ; Gulf of Manaar? and off Mount Lavinia (7h.) ; Ras el 
Millan, collected by Hartmeyer. 
GIGANTOPORA FENESTRATA (Smitt). (Plate 18. figs. 17-19.) 
Hippothoa fenestrata, Smitt, ‘Floridan Bryozoa,” p. 47, pl. 6. fig. 142 (1872). 
Gigantopora lyncoides, Ridley, Proc. Zool. Soc. London, 1881, p. 47, pl. 6. fig. 3; 
Kirkpatrick, Ann. Mag. Nat. Hist. ser. 6, vol. 1. (1888) p. 77, pl. 7. fig. 5. 
Porina ? columnata, Waters, “Fess. Chil. 8.W. Vict.,”’ Quart. Journ. Geol. Soe. 
vol, xxxvii. (1881) p. 334, pl. 18. fig. 88. 
? Porina tuberculosa, Maplestone, Proc. Roy. Soe. Vict. n. s. vol. xv. (1902) p. 23, pl. 2. 
fig. 15. 
Porina cribraria, MacGillivray, “Tert. Poly. Vict.,” Trans. Roy. Soc. Vict. vol. iv. 
p. 104, pl. 14. fig. 25 (1895). 
Gigantopora fenestrata, Thornely, ‘ Manaar,” p. 113 (1905). 
The three genera Gigantopora, Ridley, Gephyrophora, Busk, and G'aleopsis, 
Jullien & Calvet, are synonyms, and have been made for species in which 
two lateral avicularia arch over the oral aperture, forming a bridge and a 
round or elliptical opening below. However, we have avicularia making an 
arch in a similar way in Microporella and Smuttia, and it is probably not a 
character of generic importance ; and, as Kirkpatrick and I have indicated, 
Gigantopora belongs to the Schizoporellidan group ; but when Schizoporella 
is rearranged it is not likely to remain under that genus, though it may be 
au open question whether it should for the time being be placed there. 
The ovicell is but very little raised and decumbent by the peristome. In 
G. polymorpha, Busk, the position of the ovicell is not usually indicated. 
The operculum of the G. fenestrata is about the size of that of G. polymorpha 
and is straighter at the proximal edge. It is double, consisting of two 
similar separable membranes one over the other; but as there is only one 
small cylindrical specimen, I have not been able tc make full examination. 
G. fenestrata is closely related to the Italian Tertiary fossil Porina? 
duplicata *, Reuss, which, however, has only an avicularium at one side—in 
fact, a large number of zocecia have none, and when it exists it is more in 
the lip than is the case in the present species ; also the peristome in the fossil 
is more raised, and the ovicell is somewhat more distinct and narrower. 
Loc. Florida, 17 fath. (Sm.); 8.E. Brazil, 33 fath. (Adley) ; Mauritius 
(Kirkp.) ; Red Sea, lat. 16° 45’ N., long. 40° 30’ W., 26 fath., collected by 
Loffler & Siemens ; Gulf of Manaar (7’h.). 
Fossil. Victoria, Australia. 
* Waters, “North Italian Bryozoa,”’ Quart. Journ. Geol. Soc. vol. xlvii. p. 25, pl. 3. 
fig, 14, 
