146 MARINE BIOLOGY OF THE SUDANESE RED SEA. 
are no ovicells, the umbo is distinct, and the small triangular avicularia at 
each side are directed upwards, and there are also two large vicarious 
avicularia like those of Lepralia occlusa, Busk (see Pl. 14. fig. 1). Vicarious 
avicularia have not been found before, but there are so many cases in which 
they sometimes occur and sometimes do not, that it is clearly a character to 
which we must not attach too much importance. 
The appearance of S. unicornis, var. ansata, and S. linearis is very similar, 
but they can be distinguished by means of the opercula. 
A specimen from Suez in the British Museum would seem to be this species. 
It has similar vicarious avicularia, but no ovicells were found. Busk had 
marked it Duboisii, Aud., but I think we are hardly justified in considering it 
to be that species. 
SCHIZOPORELLA ARGENTEA, Hincks. (Plate 12. figs. 17, 18; Plate 13. 
mes, Io. IL.) 
Schizoporella argentea, Hincks, Ann. Mag. Nat. Hist. ser. 5, vol. vii. (1881) p. 158, pl. 9. 
fig. 6; op. cit. ser. 5, vol. xv. (1885) p. 254, pl. 9. fig. 6; Thornely, “ Manaar,’” p. 114 (1905). 
The zocecia are granular with small areolations round the border, and in 
some cases the granules near the border are arranged linearly like the 
beginning of ribs. There is a fairly large avicularium placed diagonally on 
the front, though in some pieces none are found. In the Red Sea specimens 
there is no avicularium in the aperture, nor are there any spines. The sinus 
of the aperture is very wide, and the operculum on the proximal edge has 
two projections instead of one, being quite different to any operculum yet 
met with, though reminding us of the operculum™* of the ovicelligerous 
zocecium of Fippothoa hyalina. The ovicell is large, long, perforated, and 
granular, and is closed by the operculum. 
The dorsal surface hag many large tubular projections for attachment ; but 
there is not the regularity described by Hincks, who says “ six prominent 
tubular projections,” for in the Red Sea specimens there is sometimes only 
one. There is no diaphragm separating this radicle projection, and the 
polypide may be distorted by the irregularity, or the testes may extend into 
the projection. 
There are 16-17 tentacles. 
A specimen from Tahiti, sent to me by Miss Jelly, only shows the avicularia 
to two zooecia, nor has it the oral spines, or the dorsal regularity described by 
Hincks. Apparently Hincks must have figured a somewhat exceptional 
piece, as my specimens are from the same lot as those described by him. In 
the African specimens the avicularium in the lip is more constant. 
Loe. “ Africa”’?; Tahiti; Manaar (Th.); Khor Dongola (2), Red Sea, 
Suakim (7), collected by Crossland. . 
* Quart. Journ. Geol. Soc. vol. xliii. pl. 8. fig. 43. 
