254 MARINE BIOLOGY OF THE SUDANESE RED SBA. 
RETEPORA ABYSSINICA, Var. EXPANSA, noy. 
Retepora abyssinica, Waters, pars, Journ. Linn. Soc., Zool. vol. xxi. p. 176, pl. 18. 
figs. 8, 9, 10. 
In cleaning some pieces of Retepora (from 422) entirely covered with 
sponge I have come to the conclusion that they should be separated from 
RR. abyssinica as a variety. The branches are slightly less stout than those of 
abyssinica, not so much in one plane, branching more frequently and occa- 
sionally anastomosing. The avicularium is in the aperture, directed laterally, 
and usually bifid, whereas in the type the avicularium is removed from the 
aperture and has a beak seldom bifid. The oral aperture in both is similar, 
with a labial pore, and there are in the peristome internal ridges giving the 
appearance of an oral sinus. The ovicells have a similar subtruncate lamina, 
and the dorsal surface has similar long narrow avicularia sometimes replaced 
by a pore. 
The only important difference is that the frontal avicularium instead of 
being close up to the aperture has a position nearer the middle of the zocecium 
in the type and is larger and directed downwards. 
ocr Warealion INE long. 41° E., 30 fath., collected by Siemens and Loffler. 
By a most unfortunate slip the type was referred to as from long. 41° W. 
In a specimen of Serupocellaria Jolloisii, Aud., from Ras el Millan, there 
is one raised somewkat lateral gigantic avicularium with a deeply furcate 
mandible, like that of Retepora delicatula, Busk. Although a large number 
of specimens were examined only this one gigantic avicularium has been 
found. When the radicles are long they are serrate at the end. 
In Holoporella piqmentaria, Waters, Gimsah Bay, there are a considerable 
number of small hydroids (Clava or Coryne) projecting through the zoarium, 
The large pore alluded to belonging to the two neighbouring zocecia (Journ. 
Linn. Soe., Zool. xxxi. p. 163, pl. 15. fig. 16) is for the passage of the hydroid. 
I have another Holoporella from Zanzibar infested in the same way by a 
hydroid. 
It seems that the locality which is alluded to as Nersa Makdah should be 
Mersa Makdah, the label having been misread. This volume, pp. 129, 131, 
22, Sa, ail 
