174 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
mandibular portion and the mandibular part are in quite different planes. 
The mandible is divided at the end into three or four points. 
Loe. Gulf of Manaar (7h.) ; Ras el Millan, collected by Hartmeyer. 
SMITTIA TROPICA, sp. nov. (Plate 1%. figs. 10-14.) | 
Zoarium white, incrusting. The zoccia are distinctly separated, and there 
are pores at each side of the nearly straight borders. ‘The surface is nodulated, 
and there are two oral spines. The peristome is much raised, sometimes 
dentate, but always with two internal ridges passing down the peristome and 
terminating in cardellze. There is at one or both sides near the aperture an 
avicularium directed downwards. In most cases the avicularium is linear to 
oblong, with a thin transparent mandible (fig. 12) ; in other cases there is a 
somewhat larger avicularium, beaked at each side, and these larger triangular 
avicularia have a dark thick acute mandible (fig. 11), and here the muscles 
are four or five times as large as those of the first mentioned thin linear 
avicularia. In the narrow avicularia there is an opening on each side of the 
bar as usual, but there is also a smal! round opening further removed distally 
from the bar (fig. 14). The distal end of the avicularium means the beak 
end. 
The ovicell is small, globular, thrown back, perforated, and closed by an 
ovicellular operculum (fig. 13, 0.0.), which is semicircular and about half the 
size of the oral operculum. The ovicell is formed by two layers, and pore- 
tubes pass from one to the other (fig. 13). There are minute oral glands 
and 13 tentacles. 
This very probably is the Smittia trispinosa form spathulata, Hincks *, but 
it is not the spathulata of MacGillivray. 
Loc. Ras el Millan, collected by Hartmeyer. 
Lacuytpora Cosrazit (Audouin). 
Cellepora Costaxii, Aud. “ Descrip. de l’Egypte,’’ p. 237, pl. 7. fig. 4. 
There is a small specimen in poor condition from Gimsah Bay, in which no 
ovicells or avicularia are preserved. It, however, seems to correspond with 
some British and Mediterranean specimens. 
[In consequence of the remark of a friend, I have again examined the 
British Museum specimens of Layenipora socialis, Hincks, and the collections 
of Hincks and Busk have been added since I first wrote on the group. The 
type-specimen of Hincks shows three ovicells, which are situated at the back, 
that is the neural wall of the tubular peristome. The peristome is raised 
above the ovicell, and there is a distinct area on the ovicell with some pores, 
* Ann. Mag. Nat. Hist. ser. 5, vol. xix. p. 304, pl. 9. fig. 3. 
