164 MARINE BIOLOGY OF THE SUDANESE RED SEA, 
layer of pigment is situated immediately under the external membrane, and 
the pigment is also found in the avicularium. The appearance of these 
pigment-masses is much like that of a piece of old cork. It should not be 
forgotten that there is a membrane across the bottom and the top of the 
pore-tube, but yet these pigment-cells occur not only in the pore-tubes but 
also above and below them. 
In the zocecia without polypides the opercula have near the proximal 
border a slight projection (PI. 16. fig. 10), which is irregular and sometimes 
grows into a long tube. In one case this long tube has a round body at the 
end (fig. 12), in another there are projections at various points near the base 
of this tongue, and then the narrow tube is curled at the end (fig. 13), The 
commencement of this tongue is by two slight outgrowths of three or four 
cells ; thus at first it is paired. 
We have here the commencement of the tentacular sheath, and Harmer * 
has described the budding polypide of Flustra papyrea, Pall., as derived 
from the two angles of the operculum. In H. pigmentaria [ have only seen 
the one case of the earliest stage, but several where the commencement of 
the tentacular sheath can be recognised, and there are many with the various 
digitiform processes (fig. 11). 
Similar growth occurs in other Holoporella; and in Flustra membranaceo- 
truncata, Sm., and Lepralia lonchea, Busk, I have seen a tube identical 
with fig. 12; also in Schizoporella polystomella, Reuss, there is in some 
of the zocecia a projection or round body by the operculum, which is seen 
in various stages and commences as a double excrescence. Of course we 
have to look for these growths in zocecia where the original polypide has 
died down and where a fresh growth of polypides is commencing, showing 
the importance of examining the colonies in all conditions; for specimens 
which at first seem valueless on account of containing few or no polypides 
may give valuable information on several points. It is difficult to dis- 
tinguish between the growing and the reverse or absorbing process, and 
further examination is here required before we can be quite certain of the 
interpretation. 
Loe. Khor Dongola (2) on Meleagrina margaritifera, L., collected by 
Crossland ; Ras el Millan, collected by Hartmeyer ; Gimsah Bay, Gulf of 
Suez, cellecied by Hartmeyer ; Djibouti (Golf de Badjourah), Récif de 
Marabout, Red Sea, collected by Mons. Ch. Gravier, who gave me a small 
plece. 
HOLOPORELLA VERMIFORMIS, nov. (Plate 16. figs. 4-8.) 
Zoarium incrusting, darkly pigmented, forming several layers, recumbent 
at the edges. Zocecia smooth, with large pores round the border. The base 
* “Nature of Excretory Processes,” Quart. Journ. Micros. Se. 1891, p. 188. 
