138 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
Biflustra Savartii, Smitt, Floridan Bryozoa, pt. il. p. 20, pl. 4. figs. 92-95 (1873) ; Busk, 
Zool. Chall. Exp. vol. x. pt. xxx. p, 67, pl. 14. fig. 2; Manzoni, “ Castrocaro,” p. 38, pl. 2. 
fig. 17 (1875). 3 
 Biflustra delicatula, Busk, Crag Polyzoa, p. 72, pl. 2. fig. 7 (1859) ; Manzoni, Bry. Plioc. 
Ital. 2nd cont. p. 4, pl. 1. fig. 5 (1869) ; MacGillivray, Zool. Vict. dec. vi. p. 28, pl. 57. fig. 2. 
(1881). 
There has been much uncertainty concerning this species and its range; 
for Membranipore have been obtained from many places, only differing, firstly, 
in the absence of the two small tubercles shown by Savigny, and, secondly, 
some have a broad serrate denticle at the proximal end of the opesia. 
The specimens from Suakim (7) have neither tubercle nor serrate denticle, 
whereas a small incrusting specimen on Retepora from the Red Sea, lat. 16° 
N., long. 41° W., 30 fath., collected by Siemens & Liffler, has the serrate 
denticle directed inwards towards the basal wall (fig. 13). In the specimens 
from Suakim Harbour the zoarium is at first loosely incrusting, and from 
this adnate growth arise erect cylindrical or compressed branches dividing 
dichotomously (fig. 10). 
In these there is a row of communication plates across the distal wall about 
halfway between the front and the base ; sometimes the row is double or 
irregular, with a tendency to form two groups. In a specimen of Membrani- 
pora from Penang, which has large tubercles and a narrow brown line 
surrounding the zocecia as described by Busk for MM. denticulata, the two 
distal rosette-plates are near the base in the corner. This must probably 
be separated from Savarti. 
The specimens from Suakim are fragile and have not a great amount 
of caleureous matter, and there are no denticles either in the adnate portion 
or in the branches, though in specimens from Khor Dongola (4) there are no 
denticles in the younger portion, while they occur in the older branching 
parts ; but in neither case are they found in the adnate basal cells. 
MacGillivray * says, when speaking of J. delicatula, “the serrated denticle 
at the bottom of the aperture exists only in two or three cells of the Queens- 
cliff specimen and is altogether absent in those from (Jueensland ” ; and Busk, 
in describing MW. denticulata, says “ one or two rounded or triangular eminences 
(probably ovicells) are visible on many of the cells in front and below.” The 
tubercles are not described from the Crag, nor were they found by Smitt, but 
tubercles in this group are very variable; and I therefore follow other workers 
in placing under Savartii, Aud., species with and without tubercles. The 
simplest forms of the group have no tubercles, no serrate denticle, and the 
communication pores are more or less in a line, whereas in others the line is 
broken up into two groups. There are normaily four lateral rosette-plates. 
A specimen from Zanzibar has proximal narrow cervicorn denticles, and 
another from Zanzibar contains an astonishing amount of the parenchym 
* Prod. Zool. Vict. dee. Vi. p. 28. 
